Publications by authors named "Mark Cobbold"

46 Publications

Resistance to Pyrrolobenzodiazepine Dimers Is Associated with SLFN11 Downregulation and Can Be Reversed through Inhibition of ATR.

Mol Cancer Ther 2021 03;20(3):541-552

Early Oncology R&D, AstraZeneca, Gaithersburg, Maryland.

Resistance to antibody-drug conjugates (ADCs) has been observed in both preclinical models and clinical studies. However, mechanisms of resistance to pyrrolobenzodiazepine (PBD)-conjugated ADCs have not been well characterized and thus, this study was designed to investigate development of resistance to PBD dimer warheads and PBD-conjugated ADCs. We established a PBD-resistant cell line, 361-PBDr, by treating human breast cancer MDA-MB-361 cells with gradually increasing concentrations of SG3199, the PBD dimer released from the PBD drug-linker tesirine. 361-PBDr cells were over 20-fold less sensitive to SG3199 compared with parental cells and were cross-resistant to other PBD warhead and ADCs conjugated with PBDs. Proteomic profiling revealed that downregulation of Schlafen family member 11 (SLFN11), a putative DNA/RNA helicase, sensitizing cancer cells to DNA-damaging agents, was associated with PBD resistance. Confirmatory studies demonstrated that siRNA knockdown of SLFN11 in multiple tumor cell lines conferred reduced sensitivity to SG3199 and PBD-conjugated ADCs. Treatment with EPZ011989, an EZH2 inhibitor, derepressed SLFN11 expression in 361-PBDr and other SLFN11-deficient tumor cells, and increased sensitivity to PBD and PBD-conjugated ADCs, indicating that the suppression of SLFN11 expression is associated with histone methylation as reported. Moreover, we demonstrated that combining an ataxia telangiectasia and Rad3-related protein (ATR) inhibitor, AZD6738, with SG3199 or PBD-based ADCs led to synergistic cytotoxicity in either resistant 361-PBDr cells or cells that SLFN11 was knocked down via siRNA. Collectively, these data provide insights into potential development of resistance to PBDs and PBD-conjugated ADCs, and more importantly, inform strategy development to overcome such resistance.
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http://dx.doi.org/10.1158/1535-7163.MCT-20-0351DOI Listing
March 2021

Regorafenib combined with PD1 blockade increases CD8 T-cell infiltration by inducing CXCL10 expression in hepatocellular carcinoma.

J Immunother Cancer 2020 11;8(2)

Edwin L. Steele Laboratories for Tumor Biology, Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts, USA

Background And Purpose: Combining inhibitors of vascular endothelial growth factor and the programmed cell death protein 1 (PD1) pathway has shown efficacy in multiple cancers, but the disease-specific and agent-specific mechanisms of benefit remain unclear. We examined the efficacy and defined the mechanisms of benefit when combining regorafenib (a multikinase antivascular endothelial growth factor receptor inhibitor) with PD1 blockade in murine hepatocellular carcinoma (HCC) models.

Basic Procedures: We used orthotopic models of HCC in mice with liver damage to test the effects of regorafenib-dosed orally at 5, 10 or 20 mg/kg daily-combined with anti-PD1 antibodies (10 mg/kg intraperitoneally thrice weekly). We evaluated the effects of therapy on tumor vasculature and immune microenvironment using immunofluorescence, flow cytometry, RNA-sequencing, ELISA and pharmacokinetic/pharmacodynamic studies in mice and in tissue and blood samples from patients with cancer.

Main Findings: Regorafenib/anti-PD1 combination therapy increased survival compared with regofarenib or anti-PD1 alone in a regorafenib dose-dependent manner. Combination therapy increased regorafenib uptake into the tumor tissues by normalizing the HCC vasculature and increasing CD8 T-cell infiltration and activation at an intermediate regorafenib dose. The efficacy of regorafenib/anti-PD1 therapy was compromised in mice lacking functional T cells (-deficient mice). Regorafenib treatment increased the transcription and protein expression of CXCL10-a ligand for CXCR3 expressed on tumor-infiltrating lymphocytes-in murine HCC and in blood of patients with HCC. Using -deficient mice, we demonstrate that CXCR3 mediated the increased intratumoral CD8 T-cell infiltration and the added survival benefit when regorafenib was combined with anti-PD1 therapy.

Principal Conclusions: Judicious regorafenib/anti-PD1 combination therapy can inhibit tumor growth and increase survival by normalizing tumor vasculature and increasing intratumoral CXCR3+CD8 T-cell infiltration through elevated CXCL10 expression in HCC cells.
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http://dx.doi.org/10.1136/jitc-2020-001435DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7689089PMC
November 2020

Massively parallel interrogation and mining of natively paired human TCRαβ repertoires.

Nat Biotechnol 2020 05 16;38(5):609-619. Epub 2020 Mar 16.

GigaMune, Inc., South San Francisco, CA, USA.

T cells engineered to express antigen-specific T cell receptors (TCRs) are potent therapies for viral infections and cancer. However, efficient identification of clinical candidate TCRs is complicated by the size and complexity of T cell repertoires and the challenges of working with primary T cells. Here we present a high-throughput method to identify TCRs with high functional avidity from diverse human T cell repertoires. The approach used massively parallel microfluidics to generate libraries of natively paired, full-length TCRαβ clones, from millions of primary T cells, which were then expressed in Jurkat cells. The TCRαβ-Jurkat libraries enabled repeated screening and panning for antigen-reactive TCRs using peptide major histocompatibility complex binding and cellular activation. We captured more than 2.9 million natively paired TCRαβ clonotypes from six healthy human donors and identified rare (<0.001% frequency) viral-antigen-reactive TCRs. We also mined a tumor-infiltrating lymphocyte sample from a patient with melanoma and identified several tumor-specific TCRs, which, after expression in primary T cells, led to tumor cell killing.
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http://dx.doi.org/10.1038/s41587-020-0438-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224336PMC
May 2020

MHC-restricted phosphopeptide antigens: preclinical validation and first-in-humans clinical trial in participants with high-risk melanoma.

J Immunother Cancer 2020 05;8(1)

Department of Surgery/Division of Surgical Oncology, University of Virginia School of Medicine, Charlottesville, Virginia, USA.

Background: Phosphorylated peptides presented by MHC molecules represent a new class of neoantigens expressed on cancer cells and recognized by CD8 T-cells. These peptides are promising targets for cancer immunotherapy. Previous work identified an HLA-A*0201-restricted phosphopeptide from insulin receptor substrate 2 (pIRS2) as one such target. The purpose of this study was to characterize a second phosphopeptide, from breast cancer antiestrogen resistance 3 (BCAR3), and to evaluate safety and immunogenicity of a novel immunotherapic vaccine comprising either or both of these phosphorylated peptides.

Methods: Phosphorylated BCAR3 protein was evaluated in melanoma and breast cancer cell lines by Western blot, and recognition by T-cells specific for HLA-A*0201-restricted phosphorylated BCAR3 peptide (pBCAR3) was determined by Cr release assay and intracellular cytokine staining. Human tumor explants were also evaluated by mass spectrometry for presentation of pIRS2 and pBCAR3 peptides. For the clinical trial, participants with resected stage IIA-IV melanoma were vaccinated 6 times over 12 weeks with one or both peptides in incomplete Freund's adjuvant and Hiltonol (poly-ICLC). Adverse events (AEs) were coded based on National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) V.4.03, with provision for early study termination if dose-limiting toxicity (DLT) rates exceeded 33%. The enrollment target was 12 participants evaluable for immune response to each peptide. T-cell responses were assessed by interferon-γ ELISpot assay.

Results: pBCAR3 peptides were immunogenic in vivo in mice, and in vitro in normal human donors, and T-cells specific for pBCAR3 controlled outgrowth of a tumor xenograft. The pIRS2 peptide was identified by mass spectrometry from human hepatocellular carcinoma tumors. In the clinical trial, 15 participants were enrolled. All had grade 1 or 2 treatment-related AEs, but there were no grade 3-4 AEs, DLTs or deaths on study. T-cell responses were induced to the pIRS2 peptide in 5/12 patients (42%, 90% CI 18% to 68%) and to the pBCAR3 peptide in 2/12 patients (17%, 90% CI 3% to 44%).

Conclusion: This study supports the safety and immunogenicity of vaccines containing the cancer-associated phosphopeptides pBCAR3 and pIRS2, and the data support continued development of immune therapy targeting phosphopeptides. Future studies will define ways to further enhance the magnitude and durability of phosphopeptide-specific immune responses.

Trial Registration Number: NCT01846143.
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http://dx.doi.org/10.1136/jitc-2019-000262DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7228659PMC
May 2020

Antibody-mediated delivery of viral epitopes to tumors harnesses CMV-specific T cells for cancer therapy.

Nat Biotechnol 2020 04 10;38(4):420-425. Epub 2020 Feb 10.

Massachusetts General Hospital Cancer Center and Department of Medicine, Harvard Medical School, Boston, MA, USA.

Several cancer immunotherapy approaches, such as immune checkpoint blockade and adoptive T-cell therapy, boost T-cell activity against the tumor, but these strategies are not effective in the absence of T cells specific for displayed tumor antigens. Here we outline an immunotherapy in which endogenous T cells specific for a noncancer antigen are retargeted to attack tumors. The approach relies on the use of antibody-peptide epitope conjugates (APECs) to deliver suitable antigens to the tumor surface for presention by HLA-I. To retarget cytomegalovirus (CMV)-specific CD8 T cells against tumors, we used APECs containing CMV-derived epitopes conjugated to tumor-targeting antibodies via metalloprotease-sensitive linkers. These APECs redirect pre-existing CMV immunity against tumor cells in vitro and in mouse cancer models. In vitro, APECs activated specifically CMV-reactive effector T cells whereas a bispecific T-cell engager activated both effector and regulatory T cells. Our approach may provide an effective alternative in cancers that are not amenable to checkpoint inhibitors or other immunotherapies.
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http://dx.doi.org/10.1038/s41587-019-0404-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7456461PMC
April 2020

Murine xenograft bioreactors for human immunopeptidome discovery.

Sci Rep 2019 12 6;9(1):18558. Epub 2019 Dec 6.

Center for Cancer Immunology, Massachusetts General Hospital, Boston, Massachusetts, USA.

The study of peptides presented by MHC class I and class II molecules is limited by the need for relatively large cell numbers, especially when studying post-translationally modified or otherwise rare peptide species. To overcome this problem, we pose the hypothesis that human cells grown as xenografts in immunodeficient mice should produce equivalent immunopeptidomes as cultured cells. Comparing human cell lines grown either in vitro or as murine xenografts, we show that the immunopeptidome is substantially preserved. Numerous features are shared across both sample types, including peptides and proteins featured, length distributions, and HLA-binding motifs. Peptides well-represented in both groups were from more abundant proteins, or those with stronger predicted HLA binding affinities. Samples grown in vivo also recapitulated a similar phospho-immunopeptidome, with common sequences being those found at high copy number on the cell surface. These data indicate that xenografts are indeed a viable methodology for the production of cells for immunopeptidomic discovery.
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http://dx.doi.org/10.1038/s41598-019-54700-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6898210PMC
December 2019

Dual Programmed Death Receptor-1 and Vascular Endothelial Growth Factor Receptor-2 Blockade Promotes Vascular Normalization and Enhances Antitumor Immune Responses in Hepatocellular Carcinoma.

Hepatology 2020 04 14;71(4):1247-1261. Epub 2019 Oct 14.

Edwin. L. Steele Laboratories for Tumor Biology, Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA.

Background And Aims: Activation of the antitumor immune response using programmed death receptor-1 (PD-1) blockade showed benefit only in a fraction of patients with hepatocellular carcinoma (HCC). Combining PD-1 blockade with antiangiogenesis has shown promise in substantially increasing the fraction of patients with HCC who respond to treatment, but the mechanism of this interaction is unknown.

Approach And Results: We recapitulated these clinical outcomes using orthotopic-grafted or induced-murine models of HCC. Specific blockade of vascular endothelial receptor 2 (VEGFR-2) using a murine antibody significantly delayed primary tumor growth but failed to prolong survival, while anti-PD-1 antibody treatment alone conferred a minor survival advantage in one model. However, dual anti-PD-1/VEGFR-2 therapy significantly inhibited primary tumor growth and doubled survival in both models. Combination therapy reprogrammed the immune microenvironment by increasing cluster of differentiation 8-positive (CD8 ) cytotoxic T cell infiltration and activation, shifting the M1/M2 ratio of tumor-associated macrophages and reducing T regulatory cell (Treg) and chemokine (C-C motif) receptor 2-positive monocyte infiltration in HCC tissue. In these models, VEGFR-2 was selectively expressed in tumor endothelial cells. Using spheroid cultures of HCC tissue, we found that PD-ligand 1 expression in HCC cells was induced in a paracrine manner upon anti-VEGFR-2 blockade in endothelial cells in part through interferon-gamma expression. Moreover, we found that VEGFR-2 blockade increased PD-1 expression in tumor-infiltrating CD4 cells. We also found that under anti-PD-1 therapy, CD4 cells promote normalized vessel formation in the face of antiangiogenic therapy with anti-VEGFR-2 antibody.

Conclusions: We show that dual anti-PD-1/VEGFR-2 therapy has a durable vessel fortification effect in HCC and can overcome treatment resistance to either treatment alone and increase overall survival in both anti-PD-1 therapy-resistant and anti-PD-1 therapy-responsive HCC models.
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http://dx.doi.org/10.1002/hep.30889DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7000304PMC
April 2020

Aberrant X chromosome skewing and acquired clonal hematopoiesis in adult-onset common variable immunodeficiency.

JCI Insight 2019 07 25;4(14). Epub 2019 Jul 25.

Massachusetts General Hospital, Cancer Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA.

Advances in genomic medicine have elucidated an increasing number of genetic etiologies for patients with common variable immunodeficiency (CVID). However, there is heterogeneity in clinical and immunophenotypic presentations and a limited understanding of the underlying pathophysiology of many cases. The primary defects in CVID may extend beyond the adaptive immune system, and the combined defect in both the myeloid and lymphoid compartments suggests the mechanism may involve bone marrow output and earlier progenitors. Using the methylation profile of the human androgen receptor (AR) gene as a surrogate epigenetic marker for bone marrow clonality, we examined the hematopoietic compartments of patients with CVID. Our data show that clonal hematopoiesis is common among patients with adult-onset CVID who do not have associated noninfectious complications. Nonblood tissues did not show a skewed AR methylation status, supporting a model of an acquired clonal hematopoietic event. Attenuation of memory B cell differentiation into long-lived plasma cells (CD20-CD27+CD38+CD138+) was associated with marked changes in the postdifferentiation methylation profile, demonstrating the functional consequence of clonal hematopoiesis on humoral immunity in these patients. This study sheds light on a potential etiology of a subset of patients with CVID, and the findings suggest that it is a stage of an acquired lymphocyte maturation disorder.
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http://dx.doi.org/10.1172/jci.insight.127614DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6675553PMC
July 2019

Differential Association Between Circulating Lymphocyte Populations With Outcome After Radiation Therapy in Subtypes of Liver Cancer.

Int J Radiat Oncol Biol Phys 2018 08 17;101(5):1222-1225. Epub 2018 Apr 17.

Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. Electronic address:

Purpose: Irradiation may have significant immunomodulatory effects that impact tumor response and could potentiate immunotherapeutic approaches. The purposes of this study were to prospectively investigate circulating lymphoid cell population fractions during hypofractionated proton therapy (HPT) in blood samples of liver cancer patients and to explore their association with survival.

Methods And Materials: We collected serial blood samples before treatment and at days 8 and 15 of HPT from 43 patients with liver cancer-22 with hepatocellular carcinoma (HCC) and 21 with intrahepatic cholangiocarcinoma (ICC)-enrolled in a phase 2 clinical trial. All patients received 15 fractions of proton therapy to a median dose of 58 Gy (relative biological effectiveness). We used flow cytometry to measure the changes in the fractions of total CD3, CD4, and CD8 T cells; CD4 CD25 T cells; CD4 CD127 T cells; CD3 CD8 CD25 activated cytotoxic T lymphocytes (CTLs); and CD3 CD56 natural killer cells.

Results: With a median follow-up period of 42 months, median overall survival (OS) in the study cohort was 30.6 months for HCC and 14.5 months for ICC patients. Longer OS was significantly correlated with greater CD4 CD25 T-cell (P = .003) and CD4 CD127 T-cell (P = .01) fractions at baseline only in ICC patients. In HCC patients, the fraction of activated CTLs mid treatment (at day 8) was significantly associated with OS (P = .007). These findings suggest a differential relevance of immunomodulation by HPT in these liver cancers.

Conclusions: Antitumor immunity may depend on maintenance of a sufficiently high number of activated CTLs during HPT in HCC patients and CD4 CD25 T cells and CD4 CD127 T cells prior to treatment in ICC patients. These results could guide the design of future studies to determine the optimal treatment schedules when combining irradiation with specific immunotherapy approaches.
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http://dx.doi.org/10.1016/j.ijrobp.2018.04.026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6050125PMC
August 2018

The antigenic identity of human class I MHC phosphopeptides is critically dependent upon phosphorylation status.

Oncotarget 2017 Aug 8;8(33):54160-54172. Epub 2017 Apr 8.

Cancer Immunology and Immunotherapy Centre, Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.

Dysregulated post-translational modification provides a source of altered self-antigens that can stimulate immune responses in autoimmunity, inflammation, and cancer. In recent years, phosphorylated peptides have emerged as a group of tumour-associated antigens presented by MHC molecules and recognised by T cells, and represent promising candidates for cancer immunotherapy. However, the impact of phosphorylation on the antigenic identity of phosphopeptide epitopes is unclear. Here we examined this by determining structures of MHC-bound phosphopeptides bearing canonical position 4-phosphorylations in the presence and absence of their phosphate moiety, and examining phosphopeptide recognition by the T cell receptor (TCR). Strikingly, two peptides exhibited major conformational changes upon phosphorylation, involving a similar molecular mechanism, which focussed changes on the central peptide region most critical for T cell recognition. In contrast, a third epitope displayed little conformational alteration upon phosphorylation. In addition, binding studies demonstrated TCR interaction with an MHC-bound phosphopeptide was both epitope-specific and absolutely dependent upon phosphorylation status. These results highlight the critical influence of phosphorylation on the antigenic identity of naturally processed class I MHC epitopes. In doing so they provide a molecular framework for understanding phosphopeptide-specific immune responses, and have implications for the development of phosphopeptide antigen-specific cancer immunotherapy approaches.
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http://dx.doi.org/10.18632/oncotarget.16952DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5589570PMC
August 2017

Immune dysregulation in immunodeficiency disorders: The role of T-cell receptor sequencing.

J Autoimmun 2017 Jun 8;80:1-9. Epub 2017 Apr 8.

Massachusetts General Hospital Cancer Center and Department of Medicine Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA. Electronic address:

Immune dysregulation is a prominent feature of primary immunodeficiency disorders, which commonly manifested as autoimmunity, cytopenias and inflammatory bowel disease. In partial T-cell immunodeficiency disorders, it has been proposed that the imbalance between effector and regulatory T-cells drives the breakdown of peripheral tolerance. While there is no robust test for immune dysregulation, the T-cell receptor repertoire is used as a surrogate marker, and has been shown to be perturbed in a number of immunodeficiency disorders featuring immune dysregulation including Omenn's Syndrome, Wiskott-Aldrich Syndrome, and common variable immunodeficiency. This review discusses how recent advances in TCR next-generation sequencing and bioinformatics have led to the in-depth characterization of CDR3 sequences and an exponential growth in examinable parameters. Specifically, we highlight the use of junctional diversity as a means to differentiate intrinsic T-cell defects from secondary causes of repertoire perturbation in primary immunodeficiency disorders. However, key questions, such as the identity of antigenic targets for large, expanded T-cell clonotypes, remain unanswered despite the fact that such clones are likely to play a pathogenic role in driving immune dysregulation and autoimmunity. Finally, we discuss a number of emerging technologies such as in silico reconstruction, high-throughput pairwise αβ sequencing and single-cell RNAseq that offer the potential to define the antigenic epitope and function of a given T-cell, thereby enhancing our understanding in this field.
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http://dx.doi.org/10.1016/j.jaut.2017.04.002DOI Listing
June 2017

Identification of Glycopeptides as Posttranslationally Modified Neoantigens in Leukemia.

Cancer Immunol Res 2017 05 17;5(5):376-384. Epub 2017 Mar 17.

Department of Clinical Immunology, University of Birmingham, Birmingham, United Kingdom.

Leukemias are highly immunogenic, but they have a low mutational load, providing few mutated peptide targets. Thus, the identification of alternative neoantigens is a pressing need. Here, we identify 36 MHC class I-associated peptide antigens with O-linked β--acetylglucosamine (-GlcNAc) modifications as candidate neoantigens, using three experimental approaches. Thirteen of these peptides were also detected with disaccharide units on the same residues and two contain either mono- and/or di-methylated arginine residues. A subset were linked with key cancer pathways, and these peptides were shared across all of the leukemia patient samples tested (5/5). Seven of the -GlcNAc peptides were synthesized and five (71%) were shown to be associated with multifunctional memory T-cell responses in healthy donors. An -GlcNAc-specific T-cell line specifically killed autologous cells pulsed with the modified peptide, but not the equivalent unmodified peptide. Therefore, these posttranslationally modified neoantigens provide logical targets for cancer immunotherapy. .
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http://dx.doi.org/10.1158/2326-6066.CIR-16-0280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5508727PMC
May 2017

Development of a rapid and quantitative lateral flow assay for the simultaneous measurement of serum κ and λ immunoglobulin free light chains (FLC): inception of a new near-patient FLC screening tool.

Clin Chem Lab Med 2017 Mar;55(3):424-434

Background: Serum free light chains (FLC) are sensitive biomarkers used for the diagnosis and management of plasma cell dyscrasias, such as multiple myeloma (MM), and are central to clinical screening algorithms and therapy response criteria. We have developed a portable, near-patient, lateral-flow test (Seralite®) that quantitates serum FLC in 10 min, and is designed to eliminate sample processing delays and accelerate decision-making in the clinic.

Methods: Assay interference, imprecision, lot-to-lot variability, linearity, and the utility of a competitive-inhibition design for the elimination of antigen-excess ('hook effect') were assessed. Reference ranges were calculated from 91 healthy donor sera. Preliminary clinical validation was conducted by retrospective analysis of sera from 329 patients. Quantitative and diagnostic results were compared to Freelite®.

Results: Seralite® gave a broad competitive-inhibition calibration curve from below 2.5 mg/L to above 200 mg/L, provided good assay linearity (between 1.6 and 208.7 mg/L for κ FLC and between 3.5 and 249.7 mg/L for λ FLC) and sensitivity (1.4 mg/L for κ FLC and 1.7 mg/L for λ FLC), and eliminated anomalous results from antigen-excess. Seralite® gave good diagnostic concordance with Freelite® (Roche Hitachi Cobas C501) identifying an abnormal FLC ratio and FLC difference in 209 patients with newly diagnosed MM and differentiating these patients from normal healthy donors with polyclonal FLC.

Conclusions: Seralite® sensitively quantitates FLC and rapidly identifies clinical conditions where FLC are abnormal, including MM.
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http://dx.doi.org/10.1515/cclm-2016-0194DOI Listing
March 2017

Accelerated Loss of TCR Repertoire Diversity in Common Variable Immunodeficiency.

J Immunol 2016 09 1;197(5):1642-9. Epub 2016 Aug 1.

Cancer Center, Massachusetts General Hospital, Boston MA 02114; Department of Medicine, Harvard Medical School, Charlestown, MA 02129;

Although common variable immunodeficiency (CVID) has long been considered as a group of primary Ab deficiencies, growing experimental data now suggest a global disruption of the entire adaptive immune response in a segment of patients. Oligoclonality of the TCR repertoire was previously demonstrated; however, the manner in which it relates to other B cell and T cell findings reported in CVID remains unclear. Using a combination approach of high-throughput TCRβ sequencing and multiparametric flow cytometry, we compared the TCR repertoire diversity between various subgroups of CVID patients according to their B cell immunophenotypes. Our data suggest that the reduction in repertoire diversity is predominantly restricted to those patients with severely reduced class-switched memory B cells and an elevated level of CD21(lo) B cells (Freiburg 1a), and may be driven by a reduced number of naive T cells unmasking underlying memory clonality. Moreover, our data indicate that this loss in repertoire diversity progresses with advancing age far exceeding the expected physiological rate. Radiological evidence supports the loss in thymic volume, correlating with the decrease in repertoire diversity. Evidence now suggests that primary thymic failure along with other well-described B cell abnormalities play an important role in the pathophysiology in Freiburg group 1a patients. Clinically, our findings emphasize the integration of combined B and T cell testing to identify those patients at the greatest risk for infection. Future work should focus on investigating the link between thymic failure and the severe reduction in class-switched memory B cells, while gathering longitudinal laboratory data to examine the progressive nature of the disease.
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http://dx.doi.org/10.4049/jimmunol.1600526DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4991247PMC
September 2016

Inhibition of Histone Deacetylase 6 Reveals a Potent Immunosuppressant Effect in Models of Transplantation.

Transplantation 2016 Aug;100(8):1667-74

1 Department of Renal and Transplant Surgery, University Hospitals Birmingham NHS Trust, Birmingham, United Kingdom.2 Department of Histopathology, University Hospitals Birmingham NHS Trust, Birmingham, United Kingdom.3 Department of Clinical Immunology, School of Immunity and Infection, University of Birmingham, Birmingham, United Kingdom.4 Karus Therapeutics Limited, Abingdon, Oxfordshire, United Kingdom.

Background: Current transplant immunosuppression regimens have numerous limitations. Recent evidence suggests histone deacetylase inhibitors (HDACis) may represent a class of drug with immunosuppressive properties. This study compares cyclosporin A (CyA) with the pan-HDACi suberoylanilide hydroxamic acid (SAHA) and a novel HDAC6-specific inhibitor (KA1010) in models of alloreactivity.

Methods: Proliferation and mixed lymphocyte reaction (MLR)-based assays were used to determine the immunosuppressive effect of compounds, and a murine model of allogeneic skin transplantation was adopted to assess the in vivo effects of HDAC6 inhibition.

Results: KA1010 displayed superior inhibitory effects on the activation of peripheral mononuclear cells using in vitro models of transplantation. In a 1-way MLR, KA1010 (5 μΜ) reduced parent cell proliferation from 92% to 64% (P = 0.001). A 2-way MLR, adopting IFN-γ production as a marker of alloresponse, resulting in up to 91% reduction. Dose-response curves revealed dose-dependent profiles with greater potency of HDACis over CyA (IC50 values of 82.0 nM and 13.4 nM for KA1010 and SAHA).Mice treated with KA1010 displayed no significant features of skin allograft rejection upon histological analysis at 70 days and graft survival of 80% in subjects treated with 160 mg/kg. Immunological assessment, revealed a significant increase in CD4CD25forkhead box P3 regulatory T cells (from 18% to 25%, P = 0.0002) and a corresponding reduction in CD4 T cells (from 58% to 42%, P = 0.0009).

Conclusions: HDAC6 may represent an optimal target for future immunosuppressant therapeutics with a particular role in transplantation. In this article, we have demonstrated a superior immunosuppressive effect of KA1010 over both CyA and SAHA, in the models of allotransplantation adopted.
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http://dx.doi.org/10.1097/TP.0000000000001208DOI Listing
August 2016

Inflammation drives thrombosis after Salmonella infection via CLEC-2 on platelets.

J Clin Invest 2015 Dec 16;125(12):4429-46. Epub 2015 Nov 16.

Thrombosis is a common, life-threatening consequence of systemic infection; however, the underlying mechanisms that drive the formation of infection-associated thrombi are poorly understood. Here, using a mouse model of systemic Salmonella Typhimurium infection, we determined that inflammation in tissues triggers thrombosis within vessels via ligation of C-type lectin-like receptor-2 (CLEC-2) on platelets by podoplanin exposed to the vasculature following breaching of the vessel wall. During infection, mice developed thrombi that persisted for weeks within the liver. Bacteria triggered but did not maintain this process, as thrombosis peaked at times when bacteremia was absent and bacteria in tissues were reduced by more than 90% from their peak levels. Thrombus development was triggered by an innate, TLR4-dependent inflammatory cascade that was independent of classical glycoprotein VI-mediated (GPVI-mediated) platelet activation. After infection, IFN-γ release enhanced the number of podoplanin-expressing monocytes and Kupffer cells in the hepatic parenchyma and perivascular sites and absence of TLR4, IFN-γ, or depletion of monocytic-lineage cells or CLEC-2 on platelets markedly inhibited the process. Together, our data indicate that infection-driven thrombosis follows local inflammation and upregulation of podoplanin and platelet activation. The identification of this pathway offers potential therapeutic opportunities to control the devastating consequences of infection-driven thrombosis without increasing the risk of bleeding.
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http://dx.doi.org/10.1172/JCI79070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4665792PMC
December 2015

Accounting for filter bandwidth improves the quantitative accuracy of bioluminescence tomography.

J Biomed Opt 2015 Sep;20(9):096001

University of Birmingham, PSIBS Doctoral Training Centre, Edgbaston, Birmingham B15 2TT, United KingdombUniversity of Birmingham, School of Computer Science, Edgbaston, Birmingham B15 2TT, United Kingdom.

Bioluminescence imaging is a noninvasive technique whereby surface weighted images of luminescent probes within animals are used to characterize cell count and function. Traditionally, data are collected over the entire emission spectrum of the source using no filters and are used to evaluate cell count/function over the entire spectrum. Alternatively, multispectral data over several wavelengths can be incorporated to perform tomographic reconstruction of source location and intensity. However, bandpass filters used for multispectral data acquisition have a specific bandwidth, which is ignored in the reconstruction. In this work, ignoring the bandwidth is shown to introduce a dependence of the recovered source intensity on the bandwidth of the filters. A method of accounting for the bandwidth of filters used during multispectral data acquisition is presented and its efficacy in increasing the quantitative accuracy of bioluminescence tomography is demonstrated through simulation and experiment. It is demonstrated that while using filters with a large bandwidth can dramatically decrease the data acquisition time, if not accounted for, errors of up to 200% in quantitative accuracy are introduced in two-dimensional planar imaging, even after normalization. For tomographic imaging, the use of this method to account for filter bandwidth dramatically improves the quantitative accuracy.
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http://dx.doi.org/10.1117/1.JBO.20.9.096001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5996822PMC
September 2015

Complementary IMAC enrichment methods for HLA-associated phosphopeptide identification by mass spectrometry.

Nat Protoc 2015 Sep 6;10(9):1308-18. Epub 2015 Aug 6.

1] Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA. [2] Department of Pathology, University of Virginia, Charlottesville, Virginia, USA.

Phosphorylation events within cancer cells often become dysregulated, leading to oncogenic signaling and abnormal cell growth. Phosphopeptides derived from aberrantly phosphorylated proteins that are presented on tumors and not on normal tissues by human leukocyte antigen (HLA) class I molecules are promising candidates for future cancer immunotherapies, because they are tumor specific and have been shown to elicit cytotoxic T cell responses. Robust phosphopeptide enrichments that are suitable for low input amounts must be developed to characterize HLA-associated phosphopeptides from clinical samples that are limited by material availability. We present two complementary mass spectrometry-compatible, iron(III)-immobilized metal affinity chromatography (IMAC) methods that use either nitrilotriacetic acid (NTA) or iminodiacetic acid (IDA) in-house-fabricated columns. We developed these protocols to enrich for subfemtomole-level phosphopeptides from cell line and human tissue samples containing picograms of starting material, which is an order of magnitude less material than what is commonly used. In addition, we added a peptide esterification step to increase phosphopeptide specificity from these low-input samples. To date, hundreds of phosphopeptides displayed on melanoma, ovarian cancer, leukemia and colorectal cancer have been identified using these highly selective phosphopeptide enrichment protocols in combination with a program called 'CAD Neutral Loss Finder' that identifies all spectra containing the characteristic neutral loss of phosphoric acid from phosphorylated serine and threonine residues. This methodology enables the identification of HLA-associated phosphopeptides presented by human tissue samples containing as little as nanograms of peptide material in 2 d.
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http://dx.doi.org/10.1038/nprot.2015.086DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4640213PMC
September 2015

Metabolomic perfusate analysis during kidney machine perfusion: the pig provides an appropriate model for human studies.

PLoS One 2014 12;9(12):e114818. Epub 2014 Dec 12.

Department of Renal Surgery, University Hospitals Birmingham, Birmingham, United Kingdom.

Introduction: Hypothermic machine perfusion offers great promise in kidney transplantation and experimental studies are needed to establish the optimal conditions for this to occur. Pig kidneys are considered to be a good model for this purpose and share many properties with human organs. However it is not established whether the metabolism of pig kidneys in such hypothermic hypoxic conditions is comparable to human organs.

Methods: Standard criteria human (n = 12) and porcine (n = 10) kidneys underwent HMP using the LifePort Kidney Transporter 1.0 (Organ Recovery Systems) using KPS-1 solution. Perfusate was sampled at 45 minutes and 4 hours of perfusion and metabolomic analysis performed using 1-D 1H-NMR spectroscopy.

Results: There was no inter-species difference in the number of metabolites identified. Of the 30 metabolites analysed, 16 (53.3%) were present in comparable concentrations in the pig and human kidney perfusates. The rate of change of concentration for 3-Hydroxybutyrate was greater for human kidneys (p<0.001). For the other 29 metabolites (96.7%), there was no difference in the rate of change of concentration between pig and human samples.

Conclusions: Whilst there are some differences between pig and human kidneys during HMP they appear to be metabolically similar and the pig seems to be a valid model for human studies.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0114818PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4264773PMC
January 2016

Metabolomic analysis of perfusate during hypothermic machine perfusion of human cadaveric kidneys.

Transplantation 2015 Apr;99(4):754-9

1 Department of Renal Surgery, University Hospitals Birmingham, Birmingham, United Kingdom. 2 Department of Immunity and Infection, University of Birmingham, Birmingham, United Kingdom. 3 Biomolecular NMR Spectroscopy, University of Birmingham, Birmingham, United Kingdom. 4 School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom.

Background: The metabolic processes occurring within the preserved kidney during hypothermic machine perfusion (HMP) are not well characterized. The aim of this study was to use nuclear magnetic resonance (NMR) spectroscopy to examine the metabolomic profile of HMP perfusate from human cadaveric kidneys awaiting transplantation and to identify possible discriminators between the profiles of kidneys with delayed graft function (DGF) and immediate graft function (IGF).

Methods: Perfusates from HMP kidneys were sampled at 45 min and 4 hr of preservation with the LifePort Kidney Transporter 1.0 (Organ Recovery Systems, Chicago, IL) using KPS-1. Prepared samples underwent 1-D Proton-NMR spectroscopy, and resultant spectra were analyzed. Clinical parameters were collected prospectively.

Results: Perfusate of 26 transplanted cadaveric kidneys was analyzed; 19(73%) with IGF and 7(27%) with DGF. Glucose concentrations were significantly lower in DGF kidneys compared to those with IGF at both 45 min (7.772 vs. 9.459 mM, P = 0.006) and 4 hr (8.202 vs. 10.235 mM, P = 0.003). Concentrations of inosine and leucine were significantly different between DGF and IGF kidneys at 45 min (0.002 vs. 0.013 mM, P = 0.009 and 0.011 vs. 0.006 mM, P = 0.036), and gluconate levels were also significantly different between DGF and IGF kidneys at 4 hr (49.099 vs. 59.513 mM, P = 0.009).

Conclusion: Significant metabolic activity may be occurring in kidneys during HMP. The NMR spectroscopy of the perfusate can identify differences in the metabolomic profiles of DGF and IGF kidneys that might have a predictive role in viability assessment. Modification of harmful metabolic processes may improve outcomes for HMP kidneys.
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http://dx.doi.org/10.1097/TP.0000000000000398DOI Listing
April 2015

Tracking genomic cancer evolution for precision medicine: the lung TRACERx study.

PLoS Biol 2014 Jul 8;12(7):e1001906. Epub 2014 Jul 8.

Translational Cancer Therapeutics Laboratory, University College London Cancer Institute, London, United Kingdom; Department of Medical Oncology, University College London Hospitals, London, United Kingdom; Translational Cancer Therapeutics Laboratory, London Research Institute, London, United Kingdom.

The importance of intratumour genetic and functional heterogeneity is increasingly recognised as a driver of cancer progression and survival outcome. Understanding how tumour clonal heterogeneity impacts upon therapeutic outcome, however, is still an area of unmet clinical and scientific need. TRACERx (TRAcking non-small cell lung Cancer Evolution through therapy [Rx]), a prospective study of patients with primary non-small cell lung cancer (NSCLC), aims to define the evolutionary trajectories of lung cancer in both space and time through multiregion and longitudinal tumour sampling and genetic analysis. By following cancers from diagnosis to relapse, tracking the evolutionary trajectories of tumours in relation to therapeutic interventions, and determining the impact of clonal heterogeneity on clinical outcomes, TRACERx may help to identify novel therapeutic targets for NSCLC and may also serve as a model applicable to other cancer types.
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http://dx.doi.org/10.1371/journal.pbio.1001906DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4086714PMC
July 2014

Resolving Salmonella infection reveals dynamic and persisting changes in murine bone marrow progenitor cell phenotype and function.

Eur J Immunol 2014 Aug 11;44(8):2318-30. Epub 2014 Jun 11.

MRC Centre for Immune Regulation, Institute for Microbiology and Infection, School of Immunity and Infection, Institute for Biomedical Research, Medical School, University of Birmingham, Edgbaston, Birmingham, UK.

The generation of immune cells from BM precursors is a carefully regulated process. This is essential to limit the potential for oncogenesis and autoimmunity yet protect against infection. How infection modulates this is unclear. Salmonella can colonize systemic sites including the BM and spleen. This resolving infection has multiple IFN-γ-mediated acute and chronic effects on BM progenitors, and during the first week of infection IFN-γ is produced by myeloid, NK, NKT, CD4(+) T cells, and some lineage-negative cells. After infection, the phenotype of BM progenitors rapidly but reversibly alters, with a peak ∼ 30-fold increase in Sca-1(hi) progenitors and a corresponding loss of Sca-1(lo/int) subsets. Most strikingly, the capacity of donor Sca-1(hi) cells to reconstitute an irradiated host is reduced; the longer donor mice are exposed to infection, and Sca-1(hi) c-kit(int) cells have an increased potential to generate B1a-like cells. Thus, Salmonella can have a prolonged influence on BM progenitor functionality not directly related to bacterial persistence. These results reflect changes observed in leucopoiesis during aging and suggest that BM functionality can be modulated by life-long, periodic exposure to infection. Better understanding of this process could offer novel therapeutic opportunities to modulate BM functionality and promote healthy aging.
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http://dx.doi.org/10.1002/eji.201344350DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4209805PMC
August 2014

Urinary biomarkers of acute kidney injury in deceased organ donors--kidney injury molecule-1 as an adjunct to predicting outcome.

Clin Transplant 2014 Jul 3;28(7):808-15. Epub 2014 Jun 3.

Department of Renal Transplantation, University Hospital Birmingham Foundation Trust, Birmingham, UK; MRC Centre for Immune Regulation, School of Immunity and Infection, Medical School, University of Birmingham, Birmingham, UK.

Background: Deceased kidney donors are increasingly "marginal," and many have risk factors for acute kidney injury (AKI) that may impact on subsequent renal transplant outcome. Despite this, determining the presence of AKI at the time of deceased organ donation remains difficult.

Methods: Urine samples from 182 brainstem dead multi-organ donors (all of whom donated hearts that were transplanted) were analyzed for a Luminex(™) panel of biomarkers linked with AKI. This included KIM-1, NGAL, IFN-γ, TNF-α, cystatin C, Fractalkine and vascular endothelial growth factor. Levels were correlated to early renal transplant outcomes, most specifically delayed graft function.

Results: Donor urinary KIM-1 levels were significantly higher in donors whose kidneys displayed aberrant early function (p = 0.011). Fractalkine levels showed a trend toward elevation in such donors but uncorrected this did not attain significance. No correlation occurred with the remaining biomarkers.

Conclusions: KIM-1 appears to show promise as a marker for AKI in deceased cardiac organ donors. The availability of a lateral flow device (Renastick(™) ) for KIM-1 that also demonstrates higher urinary KIM-1 levels in donors whose kidneys show aberrant initial function (p = 0.03), makes KIM-1 a potential indicator of AKI that may merit further evaluation for its application at the donor bedside.
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http://dx.doi.org/10.1111/ctr.12383DOI Listing
July 2014

The use of NGAL and IP-10 in the prediction of early acute rejection in highly sensitized patients following HLA-incompatible renal transplantation.

Transpl Int 2014 Apr 11;27(4):362-70. Epub 2014 Feb 11.

Department of Renal Transplantation, University Hospital Birmingham Foundation Trust, Edgbaston, UK.

Acute rejection is a significant problem for patients undergoing HLA-incompatible renal transplantation, affecting between 12 and 53% of patients. Any mechanism of detecting rejection in advance of current methods would offer significant benefit. This study aimed to evaluate whether serum biomarkers could predict rejection in HLAi transplants recipients. Sera from 94 HLAi transplant recipients from a single centre were analysed for a panel of biomarkers including: NGAL, KIM-1, IP-10, cystatin C, cathepsin L and VEGF. Biomarker levels pre-operatively, day 1 and at day 30 post-transplant were correlated with the development of early rejection. Significantly higher levels of IP-10 and NGAL were seen on day 1 following transplant in those patients who developed acute rejection (P < 0.001 and 0.005) and generated AUC of 0.73 and 0.67, respectively. No differences were seen for the other biomarkers or at the other time points. In this study cohort, IP-10 and NGAL have demonstrated good predictive ability for the development of acute rejection at a very early time point. They may have a role in identifying patients at higher risk for rejection and stratifying immunosuppression or surveillance.
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http://dx.doi.org/10.1111/tri.12266DOI Listing
April 2014

MHC class I-associated phosphopeptides are the targets of memory-like immunity in leukemia.

Sci Transl Med 2013 Sep;5(203):203ra125

Carter Immunology Center and Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA 22908, USA.

Deregulation of signaling pathways is a hallmark of malignant transformation. Signaling-associated phosphoproteins can be degraded to generate cancer-specific phosphopeptides that are presented by major histocompatibility complex (MHC) class I and II molecules and recognized by T cells; however, the contribution of these phosphoprotein-specific T cells to immune surveillance is unclear. We identified 95 phosphopeptides presented on the surface of primary hematological tumors and normal tissues, including 61 that were tumor-specific. Phosphopeptides were more prevalent on more aggressive and malignant samples. CD8(+) T cell lines specific for these phosphopeptides recognized and killed both leukemia cell lines and human leukocyte antigen-matched primary leukemia cells ex vivo. Notably, healthy individuals showed robust CD8(+) T cell responses against many of these phosphopeptides within the circulating memory compartment. This immunity was significantly reduced or absent in some leukemia patients. This reduction correlated with clinical outcome; however, immunity was restored after allogeneic stem cell transplantation. These results suggest that phosphopeptides may be targets of cancer immune surveillance in humans, and point to their importance for development of vaccine-based and T cell adoptive transfer immunotherapies.
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http://dx.doi.org/10.1126/scitranslmed.3006061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4071620PMC
September 2013

HLA-peptide multimer selection of adenovirus-specific T cells for adoptive T-cell therapy.

J Immunother 2013 Oct;36(8):423-31

*School of Cancer Sciences, University of Birmingham †University Medical School, Birmingham, UK.

Adenovirus (Ad) infection is a cause of significant morbidity and mortality in hematopoietic stem cell transplant recipients and virus-specific immunotherapy is one option for improved control. Cellular immunity is an important component in suppression of Ad replication but the frequency and population distribution of Ad-specific CD8 T cells has not been systematically investigated. This is an important question in relation to the potential use of these cells for adoptive transfer. To address this question, HLA-peptide multimers were generated for 8 HLA class I-restricted Ad epitopes, which are highly conserved across Ad species. Epitope-specific CD8 T cells from healthy donors were identified by tetramer staining and HLA class I A*01-restricted TDL peptide staining T cells were characterized in relation to frequency, phenotype, and function. The cells demonstrated a minimally differentiated central memory phenotype (CD45RA, CD45RO, CCR7, CD62L, CD27, CD28, and CD57) and were able to produce IFN-γ and proliferate extensively upon antigen stimulation in vitro. After proliferation, the phenotype switched to CD45RO, although it is interesting to note that CCR7 expression was retained. Despite their low frequency, tetramer-staining cells could be enriched with magnetic bead technology. Their characteristics should permit rapid establishment in vivo post adoptive transfer, increasing therapeutic options for patients with Ad infection. This is the first reported characterization of Ad-specific tetramer-staining T cells with a view to adoptive transfer to hematopoietic stem cell transplant patients with Ad infection. The efficacy of these cells needs to be further evaluated in the setting of a clinical trial.
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http://dx.doi.org/10.1097/CJI.0b013e3182a8029eDOI Listing
October 2013

Development of a highly-sensitive multi-plex assay using monoclonal antibodies for the simultaneous measurement of kappa and lambda immunoglobulin free light chains in serum and urine.

J Immunol Methods 2013 May 4;391(1-2):1-13. Epub 2013 Feb 4.

Clinical Immunology Service, School of Immunity and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom.

Monoclonal κ and λ immunoglobulin free light chain (FLC) paraproteins in serum and urine are important markers in the diagnosis and monitoring of B cell dyscrasias. Current nephelometric and turbidimetric methods that use sheep polyclonal antisera to quantify serum FLC have a number of well-observed limitations. In this report, we describe an improved method using specific mouse anti-human FLC monoclonal antibodies (mAbs). Anti-κ and anti-λ FLC mAbs were, separately, covalently coupled to polystyrene Xmap® beads and assayed, simultaneously, in a multi-plex format by Luminex® (mAb assay). The mAbs displayed no cross-reactivity to bound LC, the alternate LC type, or other human proteins and had improved sensitivity and specificity over immunofixation electrophoresis (IFE) and Freelite™. The assay gives good linearity and sensitivity (<1 mg/L), and the competitive inhibition format gave a broad calibration curve up to 437.5 mg/L and prevented anomalous results for samples in antigen excess i.e. high FLC levels. The mAbs displayed good concordance with Freelite™ for the quantitation of normal polyclonal FLC in plasma from healthy donors (n=249). The mAb assay identified all monoclonal FLC in serum from consecutive patient samples (n=1000; 50.1% with monoclonal paraprotein by serum IFE), and all FLC in a large cohort of urine samples tested for Bence Jones proteins (n=13090; 22.8% with monoclonal κ, 9.0% with monoclonal λ, and 0.8% with poly LC detected by urine IFE). Importantly this shows that the mAbs are at least close to the ideal of detecting FLC from all patients and neoplastic plasma cell clones. Given the overall effectiveness of the anti-FLC mAbs, further clinical validation is now warranted on serial samples from a range of patients with B cell disorders. Use of these mAbs on other assay platforms should also be investigated.
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http://dx.doi.org/10.1016/j.jim.2013.01.014DOI Listing
May 2013

Purification of antibodies to O antigen of Salmonella Typhimurium from human serum by affinity chromatography.

J Immunol Methods 2013 Jan 8;387(1-2):199-210. Epub 2012 Nov 8.

Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy.

Nontyphoidal Salmonellae (NTS) are a common cause of bacteraemia in children and HIV-infected adults in Sub-Saharan Africa. We have previously shown that antibodies play a key role in both bactericidal and cellular mechanisms of immunity to NTS, but found that high concentrations of antibody to Salmonella Typhimurium O antigen (OAg) in the serum of some HIV-infected African adults is associated with impaired killing of NTS. To further investigate the function of antibodies to the OAg of NTS, we developed a method to purify these antibodies from human serum by affinity chromatography. Purified Salmonella Typhimurium OAg was activated with adipic acid dihydrazide (ADH) via two different chemistries before linking to N-hydroxysuccinamide-Sepharose resin: one ADH molecule was introduced per OAg chain on its terminal 3-deoxy-D-manno-octulosonic acid sugar (OAg-ADH), or multiple ADH molecules were attached along the OAg chain after oxidation with sodium periodate (OAgoxADH). Both resulting columns worked well when tested with commercial polyclonal anti-O:4,5 antibodies from rabbit serum. Over 90% of the applied antibodies bound to the resin and 89% of these antibodies were then eluted as detected by ELISA. OAg-ADH was preferred as the method for OAg derivatisation as it does not modify the saccharide chain and can be applied to OAg from different bacteria. Both columns were able to bind OAg-specific antibodies in human serum, but antibody recovery was initially low. Different elution buffers were tested and different amounts of OAg-ADH were linked to the resin to improve the yield. Optimal recovery (51%) was obtained by loading 1mg of activated OAg per ml of resin and eluting with 0.1M glycine, 0.1M NaCl pH2.4. The column matrix could be regenerated following elution with no detectable loss in performance for over ten uses. This method offers the potential to purify antibodies to Salmonella OAg from polyclonal serum following vaccination or natural exposure to Salmonella and so investigate the functionality and diversity of the antibody response to OAg.
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http://dx.doi.org/10.1016/j.jim.2012.10.015DOI Listing
January 2013