Primary Antigen-Specific B Cells: A Novel Approach to Cellular-Based Immunotherapy.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3717-3717
Author(s):  
Tahamtan Ahmadi ◽  
Nathalie Weizmann ◽  
Yvonne A. Efebera ◽  
David H. Sherr
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Mhc Class I ◽  
Class I ◽  
Protein Antigens ◽  
Cognate Protein ◽  
Activated B Cells

Abstract Background: The potential for CD40 ligand (CD40L)-activated B cells to serve as antigen-presenting cells (APC) for cell-based immunotherapy has been suggested. Unlike dendritic cells (DC), CD40L-activated B cell populations are readily expandable in vitro. In addition, antigen-specific B cells may efficiently uptake, process, and present cognate protein antigens. Nevertheless, important questions regarding the relative efficacy of CD40L-activated B cells as cell-based vaccines remain. Here, we exploited the unique ability of B cells to uptake antigen through their B cell receptor (BCR) and the propensity for CD40L-activated B cells, including antigen-specific clones, to grow in culture and to process cognate protein antigens to determine if CD40L-activated B cells represent a suitable substitute for dendritic cells for cell-based immunotherapy. Methods: As a head to head comparison between CD40L-activated B cells and mature DC, CD40L-activated B cells and bone marrow-derived DC were pulsed with MHC II- or MHC I-restricted self protein-derived (MOG; MBP) peptides and tested for their ability to induce proliferation of CD4+ or CD8+ clones. To compare processing and presentation of foreign protein antigens, C57BL/6 mice were immunized with 200 mg NP-BSA or an equivalent volume of PBS emulsified in CFA, sacrificed 10 days later and splenocytes obtained to generate antigen-specific CD40L-activated B cells and T cells. Bone marrow cells from PBS/CFA immunized mice were used to generate DCs. CD40L-activated (antigen-specific) B cells and DC were pulsed with NP-BSA, NP-CGG, or BSA and assayed for their ability to induce proliferation of primary T cells. Results: B cell populations were readily expanded by culture on CD40L transfected L cells. CD40L stimulation significantly up-regulated MHC class I and II expression and induced expression of CD80 and CD86 to levels similar to those detected on mature DCs. CD40L-activated B cells were comparable to DCs when presenting MHC class I- or II-restricted self-peptides to T cell clones. When presenting cognate protein antigen (NP-BSA or BSA) to primary T cells, CD40L-activated B cells from NP-BSA immunized mice were as efficient as DC, both of which induced a 13–15 fold increase in T cell proliferation. To determine if the hapten moiety is sufficient to increase antigen up-take and presentation, DCs and CD40L-activated B cells from NP-BSA immunized mice were pulsed with NP-CGG and used as APC for T cells from NP-BSA immunized mice. DCs induced significant responses comparable to those seen with BSA and NP-BSA. Activated B cells from NP-BSA-immunized mice induced significantly higher responses to NP-CGG than activated B cells from control PBS/CFA “immunized” mice, although these responses were lower than those generated with dendritic cells. Conclusion:CD40L-activated B cells can be readily expanded in vitroand significantly up-regulate co-stimulatory molecules CD80 and CD86 to levels comparable to mature DCs,CD40L-activated B cells present MHC class I- and II-restricted self-peptides to T cell clones as efficiently as mature DCs,Antigen-primed B cells are as efficient at presenting cognate protein antigens as DCs, Immunization with a hapten-carrier is sufficient to induce hapten-specific B cells which, when activated with CD40L, effectively present unrelated neoantigens conjugated with the hapten. The data suggest that CD40L-activated B cells represent an important alternative APC for immunotherapy, particularly when previously educated to protein or haptenic determinants.

scholarly journals A quantitative analysis of antigen-presenting cell function: activated B cells stimulate naive CD4 T cells but are inferior to dendritic cells in providing costimulation.

1994 ◽  
Vol 180 (5) ◽  
pp. 1829-1840 ◽  
Author(s):  
D J Cassell ◽  
R H Schwartz
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Quantitative Analysis ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cd4 T Cells ◽  
Costimulatory Signals ◽  
Antigen Presenting ◽  
Activated B Cells

Ligation of CD28 on CD4 Th1 clones and freshly isolated mixtures of naive and memory CD4 T cells triggered their T cell receptors (TCR) is sufficient to induce the costimulatory signals necessary for interleukin 2 (IL-2) production by these cells. CTLA-4-reactive ligands expressed on antigen-presenting cells (APC) are critical in providing costimulatory signals to these T cell populations. We demonstrate that these activation characteristics apply equally to purified naive CD4 T cells. Because B cell blasts express CTLA-4-reactive ligands and high levels of adhesion and major histocompatibility complex class II molecules, they would be expected to engage both the TCR and CD28 and consequently stimulate IL-2 production by naive CD4 T cells. Using purified populations of cells in limiting dilution cultures, we have carried out a quantitative analysis of the interaction between naive CD4 T cells and either activated B or dendritic cells. We demonstrate that B cell blasts stimulate a high frequency of naive CD4 T cells. Slight differences in TCR signaling efficiency between the two APC types were observed. Even at optimal peptide concentrations, however, the amount of IL-2 made by individual T cells was fourfold lower in response to B cell blasts than to dendritic cells. This relative deficiency of activated B cells was due to their inability to optimally costimulate naive CD4 T cells.

scholarly journals T Cell Accumulation in B Cell Follicles Is Regulated by Dendritic Cells and Is Independent of B Cell Activation

2003 ◽  
Vol 197 (2) ◽  
pp. 195-206 ◽  
Author(s):  
Simon Fillatreau ◽  
David Gray
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
B Cell Activation ◽  
Cell Accumulation ◽  
Antigen Presenting ◽  
Deficient Mice

We investigated the mechanism of CD4 T cell accumulation in B cell follicles after immunization. Follicular T cell numbers were correlated with the number of B cells, indicating B cell control of the niche that T cells occupy. Despite this, we found no role for B cells in the follicular migration of T cells. Instead, T cells are induced to migrate into B cell follicles entirely as a result of interaction with dendritic cells (DCs). Migration relies on CD40-dependent maturation of DCs, as it did not occur in CD40-deficient mice but was reconstituted with CD40+ DCs. Restoration was not achieved by the activation of DCs with bacterial activators (e.g., lipopolysaccharide, CpG), but was by the injection of OX40L–huIgG1 fusion protein. Crucially, the up-regulation of OX40L (on antigen-presenting cells) and CXCR-5 (on T cells) are CD40-dependent events and we show that T cells do not migrate to follicles in immunized OX40-deficient mice.

scholarly journals Interleukin 2 induces antigen-reactive T cell lines to secrete BCGF-I.

1983 ◽  
Vol 158 (6) ◽  
pp. 2024-2039 ◽  
Author(s):  
M Howard ◽  
L Matis ◽  
T R Malek ◽  
E Shevach ◽  
W Kell ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Line ◽  
Cell Lines ◽  
Interleukin 2 ◽  
Activated T Lymphocytes ◽  
T Cell Lines ◽  
Activated B Cells

Antigen-activated T lymphocytes produce within 24 h of stimulation a factor that is indistinguishable biochemically and functionally from the B cell co-stimulating growth factor, BCGF-I, originally identified in induced EL4 supernatants: Supernatants from antigen-stimulated T cell lines are not directly mitogenic for resting B cells, but synergize in an H-2-unrestricted manner with anti-Ig activated B cells to produce polyclonal proliferation but not antibody-forming-cell development; biochemical studies reveal the B cell co-stimulating factor present in antigen-stimulated T cell line supernatants is identical by phenyl Sepharose chromatography and isoelectric focusing (IEF) to EL4 supernatant BCGF-I. We thus conclude that normal T cells produce BCGF-I in response to antigenic stimulation. Analysis of the mechanism of BCGF-I production by antigen-stimulated T cells showed that optimum amounts of BCGF-I were obtained as quickly as 24 h post-stimulation, and that the factor producing cells in the T cell line investigated bore the Lyt-1+2- phenotype. As few as 10(4) T cells produced sufficient BCGF-I to support the proliferation of 5 X 10(4) purified anti-Ig activated B cells. Finally, the activation of normal T cell lines to produce BCGF-I required either antigen presented in the context of syngeneic antigen-presenting cells (APC) or interleukin 2 (IL-2).

Non-Cognate Cytotoxic T Cells Can Be Retargeted Against CD20 Positive Tumour Cells Using [Fab' × MHC Class I/Peptide] Conjugates.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2838-2838
Author(s):  
Angela D Hamblin ◽  
Ben CR King ◽  
Ruth R French ◽  
Claude H Chan ◽  
Alison L Tutt ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Mhc Class I ◽  
Peripheral Blood ◽  
Class I ◽  
B Cell Depletion ◽  
Cytokine Release ◽  
Anti Cd20

Abstract Abstract 2838 To circumvent cytotoxic T lymphocyte (CTL) tolerance of tumour-associated antigens, the concept of redirecting CTLs against non-cognate targets has developed. One way of doing this is to use bispecific antibodies comprising anti-CD3 and anti-tumour antigen moieties. Unfortunately, this is frequently associated with unacceptable toxicity due to inflammatory cytokine release. As an alternative our approach has been to use a bivalent conjugate recognising a tumour antigen (through an antibody fragment) and a defined population of CTLs (specific for a single antigenic peptide e.g. viral epitope) through peptide presented in the context of recombinant MHC class I. We have produced a conjugate consisting of an anti-human CD20 Fab' fragment joined via a chemical crosslinker (succinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate) to murine MHC class I/peptide (Kbα1-α3 domains/β2microglobulin presenting the ovalbumin-derived peptide SIINFEKL; expressed bacterially as a continuous polypeptide single chain trimer after Yu et al, J Immunol 2002). Size exclusion chromatography allowed purification of conjugates with [Fab':MHC class I/peptide] ratios of 1:1 and 2:1 (F2 and F3 respectively). In vitro both constructs were able to redirect the transgenic murine CTL line OT-1 (specific for KbSIINFEKL) to lyse human CD20+ tumour cells (lymphoblastoid Daudi cell line) at effector: target ratios of 10:1. This lysis could be blocked by the addition of 100 fold excess of either anti-CD20 F(ab')2 or the Kb/SIINFEKL-specific antibody 25D1. The constructs were also able to cause in vitro proliferation of naïve OT-1 cells (but not irrelevant CD8+ T cells) in the presence of human CD20+ cells in both thymidine incorporation and CFSE dilution assays. Using a human CD20 transgenic mouse model (Ahuja et al, J Immunol 2007) we have evaluated both constructs in vivo for their ability to redirect adoptively transferred OT-1 cells to deplete B cells from the peripheral blood. A single dose of 1 nmole F3 and 2 nmole F2 caused respectively up to 95% and 85% B cell depletion at day 7. The efficacy of lower doses suggested a dose: response relationship. As a marker of toxicity, we have measured cytokine levels at 2, 8 and 24 hours following a dose of 1 nmole F3 and compared them to those seen after administration of an [anti-CD3 × anti-CD20] bispecific F(ab')2 at a dose (0.5 nmole) which produced similar day 7 peripheral blood B cell depletion: phosphate-buffered saline was given as a negative control. Maximal cytokine release was seen at 2 hours with the levels of IL-4, IL-5, KC, IL-2 and IL-10 being lower after administration of the F3 than after the bispecific F(ab')2. However, interestingly, the F3 resulted in greater IL-12 release. Overall these data suggest that [Fab' × MHC class I/peptide] constructs have the potential to redirect non-cognate CTLs to deplete CD20+ malignant B cells from the peripheral blood and that this is associated with a lower level of cytokine release than a similarly efficacious dose of an anti-CD3-containing bispecific F(ab')2. Furthermore, the ability of [Fab' × MHC class I/peptide] constructs to cause proliferation of OT-1 cells in vitro suggests it may be possible to use a single molecule to both generate a secondary cytotoxic T cell response and subsequently to retarget it, increasing the viability of the approach if adopted in the clinic. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Notch1-Activated B Cells Have an Immunomodulatory Function Enhancing Th2 and Treg Immune Response Via IL-33-ST2 Pathway

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 130-130
Author(s):  
Hiroshi Arima ◽  
Momoko Nishikori ◽  
Yasuyuki Otsuka ◽  
Kiyotaka Izumi ◽  
Wataru Kishimoto ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Research Funding ◽  
Pharmaceutical Research ◽  
Fate Decision ◽  
Activated B Cells

Abstract Notch1 signaling pathway is involved in T-cell fate decision and development, but it is also known to be activated in B cells upon anti-IgM or LPS stimulation. In addition to its physiological upregulation in B cells, Notch1 signaling is often aberrantly activated in several lymphoid malignancies of B-cell origin, such as classical Hodgkin lymphoma, mantle cell lymphoma and chronic lymphocytic leukemia. However, functional roles of Notch1 in B cells have not been well elucidated to date. Here we report a novel immunomodulatory role of Notch1-activated B cells that alters T-cell immune response in an IL-33-dependent manner. Functional analysis of Notch1 in mature B cells had been hampered by its substitutability for Notch2, which is involved in early B-cell fate decision towards marginal zone B cells (Zhang et. al. J Immunol 2013). To eliminate such irrelevant effect of Notch1 on early B-cell differentiation, we generated a mouse model in which Notch1 intracellular domain (NICD), a constitutively active form of Notch1, began to be expressed in mature B cells after AICDA promoter-dependent Cre expression in germinal centers (StopFloxed-NICD Tg mice×Aicda-Cre mice, hereby designated as NICD Tg mice). In this mouse model, NICD transgene was expressed in about 5% of total splenic B cells, with normal B cell maturation and differentiation. Alternatively, subsets of splenic CD4+ T cells were significantly altered, with increase in Th2 and Treg cells and decrease in Th1 and Th17 cells. IFN-γ production by CD8+ T cells was also significantly reduced. Consequently, NICD Tg mice were susceptible to fungal infections, and more importantly, they began to die of spontaneous malignant neoplasms such as sarcoma and lymphoma at 9 months of age. The tumor development was further increased when TP53 gene was heterozygously deleted in NICD Tg mice. None of the tumors having developed in NICD Tg mice expressed the NICD transgene, suggesting that these tumors did not develop as a result of direct oncogenic effect of NICD. As serum levels of IFN-γ and TNF-α were significantly lower in NICD Tg mice than in control mice, it was rather suggested that these tumors had developed under a condition of suppressed anti-tumor immunity. To elucidate the mechanism of immunomodulatory activity of Notch1-activated B cells, we performed a comparative gene expression analysis using B cells from NICD Tg and control mice. Among several candidate genes whose expression levels were increased in Notch1-activated B cells, we focused on elevated IL-33 as a potential cause for the immunomodulation. Upregulation of IL-33 protein in Notch1-activated B cells was validated by intracellular cytokine flow cytometry. IL-33 is a cytokine that is expressed in nuclei of broad types of cells in their resting state. However, we found that it was also present in the cytoplasm of Notch1-activated B cells, suggesting that IL-33 is actively produced in these cells. To confirm whether extracellular release of IL-33 from B cells was enhanced through Notch1, we cultured splenic B cells from wild-type mice with LPS stimulation in the presence of L cells with or without Notch1 ligand Delta-like 1 (Dll1) expression. We found that IL-33 secretion from B cells was increased twofold in the presence of Dll1-positive compared to Dll1-negative L cells. As expected, the Dll1-mediated increase in IL-33 levels was successfully blocked by DAPT, a Notch signaling inhibitor. To determine whether the IL-33 secreted from Notch1-activated B cells was responsible for the functional modulation of T cells, we cultured wild-type CD4+ T cells with B cells from NICD Tg or control mice, and measured cytokine levels produced by T cells. As a result, IL-4, IL-13 and IL-10 secretion was markedly increased when T cells were cocultured with Notch1-activated B cells. Strikingly, the increase in these Th2- and Treg-associated cytokine levels was completely canceled by addition of a blocking antibody against the IL-33 receptor ST2. In summary, we have shown that Notch1-activated B cells have a novel immunomodulatory function to alter T-cell immunity towards Th2 and Treg immune response via IL-33 secretion, thereby suppressing cellular immunity. This immunomodulatory mechanism may potentially be utilized by Notch1-activated B-cell neoplasms to escape anti-tumor immunity, and we propose that the Notch1-IL-33-ST2 axis can be a promising target for immunotherapy of lymphoid malignancies. Disclosures Nishikori: Kyowa Kirin: Honoraria; Eisai: Honoraria, Research Funding; Janssen Pharmaceutical: Honoraria. Takaori-Kondo:Alexion Pharmaceuticals: Research Funding; Mochida Pharmaceutical: Research Funding; Shionogi: Research Funding; Eisai: Research Funding; Takeda Pharmaceutical: Research Funding; Astellas Pharma: Research Funding; Kyowa Kirin: Research Funding; Chugai Pharmaceutical: Research Funding; Pfizer: Research Funding; Janssen Pharmaceuticals: Speakers Bureau; Merck Sharp and Dohme: Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Toyama Chemical: Research Funding; Cognano: Research Funding.

scholarly journals T-independent and T-dependent steps in the murine B cell response to antiimmunoglobulin.

1987 ◽  
Vol 166 (2) ◽  
pp. 506-519 ◽  
Author(s):  
M L Birkeland ◽  
L Simpson ◽  
P C Isakson ◽  
E Pure
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Response ◽  
Buoyant Density ◽  
S Phase ◽  
And Function ◽  
Further Development

Sepharose-anti-Ig and purified populations of small, high-density B cells have been used to study the formation and function of B lymphoblasts. Sepharose-anti-Ig converts small, Ia-poor B cells with a high-buoyant density to large, Ia-rich, B blasts with a low-buoyant density. We find that this response proceeds efficiently in the absence of IL-4 (BSF-1) as well as most T cells, macrophages, and dendritic cells. Further development of the blasts requires an additional stimulus, such as LPS or the conditioned medium of stimulated EL-4 thymoma cells. Within 6 h, blasts begin to enter S phase and within 24 h most divide. At later times (48-72 h) most of the blasts are actively secreting IgM. Recombinant IL-1, -2, -3, and -4 have little or no effect on the B blasts, and a neutralizing mAb to IL-4 does not block the response to EL-4 Sn. We conclude that Sepharose-anti-Ig induces B cell blastogenesis in a T-independent fashion and that these blasts represent a highly enriched population of cells that respond to distinct, T cell-derived lymphokines.

scholarly journals Constitutive Expression of Interleukin (IL)-4 In Vivo Causes Autoimmune-type Disorders in Mice

1997 ◽  
Vol 185 (2) ◽  
pp. 329-340 ◽  
Author(s):  
Klaus J. Erb ◽  
Beate Rüger ◽  
Maja von Brevern ◽  
Bernhard Ryffel ◽  
Annelise Schimpl ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Mhc Class I ◽  
Mhc Class Ii ◽  
Neutralizing Antibodies ◽  
Ex Vivo ◽  
Constitutive Expression ◽  
Class I

The transgenic (tg) expression of interleukin (IL)-4 under the control of a major histocompatibility complex (MHC) class I promoter leads to B cell hyperactivity in mice, characterized by increased B cell surface MHC class II and CD23 expression, elevated responsiveness of the B cells to polyclonal ex vivo stimulation, and increased immunoglobulin (Ig)G1 and IgE serum levels. Tg mice develop anemia, glomerulonephritis with complement and immune deposition in the glomeruli, and show increased production of autoantibodies. Treatment of IL-4 tg mice with anti-IL-4 neutralizing antibodies protected the mice from disease development, showing that IL-4 was responsible for the observed disorders. Deletion of superantigen responsive autoreactive T cells in the IL-4 tg mice was normal and treatment of mutant mice with deleting anti-CD4 antibodies failed to ablate the onset of autoimmune-like disease, suggesting that CD4+T cells were not the primary cause of the disorders. Furthermore, the deletion of B cells reacting against MHC class I molecules was also normal in the IL-4 tg mice. Therefore the most likely explanation for the increased production of autoantibodies and the autoimmunelike disorders is that IL-4 acts directly on autoreactive B cells by expanding them in a polyclonal manner. Taken together our results show that inappropriate multi-organ expression of IL-4 in vivo leads to autoimmune-type disease in mice.

scholarly journals CpG-Containing Oligonucleotides Are Efficient Adjuvants for Induction of Protective Antiviral Immune Responses with T-Cell Peptide Vaccines

1999 ◽  
Vol 73 (5) ◽  
pp. 4120-4126 ◽  
Author(s):  
Annette Oxenius ◽  
Marianne M. A. Martinic ◽  
Hans Hengartner ◽  
Paul Klenerman
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cells ◽  
Cell Surface ◽  
B Cell ◽  
Challenge Infection ◽  
Cpg Odn ◽  
Surface Binding ◽  
Cpg Odns

ABSTRACT Synthetic nonmethylated oligonucleotides containing CpG dinucleotides (CpG-ODNs) have been shown to exhibit immunostimulatory activity. CpG-ODNs have the capacity to directly activate B cells, macrophages, and dendritic cells, and we show here that this is reflected by cell surface binding of oligonucleotides to these cell subsets. However, T cells are not directly activated by CpG-ODNs, which correlates with the failure to bind to the T-cell surface. Efficient competition for CpG-induced B-cell activation by non-CpG-containing oligonucleotides suggests that oligonucleotides might bind to an as yet undefined sequence-nonspecific receptor prior to cellular activation. Induction of protective T-cell responses against challenge infection with lymphocytic choriomeningitis virus (LCMV) or with recombinant vaccinia virus expressing the LCMV glycoprotein was achieved by immunizing mice with the immunodominant major histocompatibility complex class I-binding LCMV glycoprotein-derived peptide gp33 together with CpG-ODNs. In these experiments, B cells, potentially serving as CpG-ODN-activated antigen-presenting cells (APCs), were not required for induction of protective immunity since CpG-ODN–gp33-immunized B-cell-deficient mice were equally protected against challenge infection with both viruses. This finding suggested that macrophages and/or dendritic cells were sufficiently activated in vivo by CpG-ODNs to serve as potent APCs for the induction of naive T cells. Furthermore, treatment with CpG-ODN alone induced protection against infection with Listeria monocytogenes via antigen-independent activation of macrophages. These data suggest that CpG activation of macrophages and dendritic cells may provide a critical step in CpG-ODN adjuvant activity.

scholarly journals T Cell Positive B Cell Negative Flow Cytometry Crossmatch (FCXM): Frequency, HLA-Locus Specificity, and Mechanisms Among 3073 Clinical FCXM Tests

2021 ◽  
Author(s):  
Prabhakar Putheti ◽  
Vijay Sharma ◽  
Rex Friedlander ◽  
Arvind Menon ◽  
Darshana Dadhania ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Rank Correlation ◽  
Class I ◽  
Igg Antibodies ◽  
Hla Antibodies ◽  
Hla Class I Antigens

Background. A T cell positive and B cell negative (T+B-) flow cytometry crossmatch (FCXM) result remains a conundrum since HLA-class I antigens are expressed on both T and B cells. We investigated the frequency, HLA specificity of the antibodies and mechanisms for the T+B- FCXM result. Methods. We analyzed 3073 clinical FCXM tests performed in an American Society of Histocompatibility and Immunogenetics accredited histocompatibility laboratory. The sera associated with the T+B- FCXM were also tested for donor HLA IgG antibodies using LABScreen single antigen assays. Results. Among the 3073 FCXM tests, 1963 were T-B-, 811 were T-B+, 274 were T+B+, and 25 were T+B-. IgG antibodies directed at donor HLA-A, B, or Cw locus determined antigens (DSA) were identified in all 25 sera and the summed mean fluorescence intensity (MFI) of DSA ranged from 212 to 53,187. Correlational analyses identified a significant association between the summed MFI of class I DSA, and the median channel fluorescence (MCF) of T cells treated with the recipient serum (Spearman rank correlation, rs=0.34, P=0.05) but not with the MCF of B cells (rs=0.23, P=0.24). We identified that differential binding of anti-HLA antibodies to T cells and B cells and the B cell channel shift threshold used to classify a B cell FCXM are potential contributors to a T+B- FCXM result. Conclusions. Our analysis of 3073 FCXM, in addition to demonstrating that HLA antibodies directed at HLA-A, B or Cw locus are associated with a T+B- result, identified mechanisms for the surprising T+B- FCXM result.

scholarly journals Human Dendritic Cells Skew Isotype Switching of CD40-activated Naive B Cells towards IgA1 and IgA2

1997 ◽  
Vol 185 (11) ◽  
pp. 1909-1918 ◽  
Author(s):  
Jérôme Fayette ◽  
Bertrand Dubois ◽  
Stéphane Vandenabeele ◽  
Jean-Michel Bridon ◽  
Béatrice Vanbervliet ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Culture Conditions ◽  
Lymphoid Organs ◽  
Cell Growth And Differentiation ◽  
Secondary Lymphoid Organs

Within T cell–rich areas of secondary lymphoid organs, interdigitating dendritic cells recruit antigen-specific T cells that then induce B cells to secrete Igs. This study investigates the possible role(s) of dendritic cells in the regulation of human B cell responses. In the absence of exogenous cytokines, in vitro generated dendritic cells (referred to as Dendritic Langerhans cells, D-Lc) induced surface IgA expression on ∼10% of CD40-activated naive sIgD+ B cells. In the presence of IL-10 and TGF-β, a combination of cytokines previously identified for its capacity to induce IgA switch, D-Lc strongly potentiated the induction of sIgA on CD40-activated naive B cells from 5% to 40–50%. D-Lc alone did not induce the secretion of IgA by CD40-activated naive B cells, which required further addition of IL-10. Furthermore, D-Lc skewed towards the IgA isotype at the expense of IgG, the Ig production of CD40-activated naive B cells cultured in the presence of IL-10 and TGF-β. Importantly, under these culture conditions, both IgA1 and IgA2 were detected. In the presence of IL-10, secretion of IgA2 by CD40-activated naive B cells could be detected only in response to D-Lc and was further enhanced by TGF-β. Collectively, these results suggest that in addition to activating T cells in the extrafollicular areas of secondary lymphoid organs, human D-Lc also directly modulate T cell–dependent B cell growth and differentiation, by inducing the IgA isotype switch.

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