Transforming growth factor beta (TGF beta) directs IgA1 and IgA2 switching in human naive B cells.
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Antibodies, Monoclonal↗
Biomedical subjects
T Defrance
Publications and source records attributed to T Defrance.
Modulation of B lymphocyte proliferation inside the germinal center.
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Animals↗
The vitronectin receptor (alpha v beta 3) is implicated, in cooperation with P-selectin and platelet-activating factor, in the adhesion of monocytes to activated endothelial cells.
In this study we have investigated the presence on endothelial cells of potential glycoprotein receptors, other than P-selectin, which are involved in the adhesion of monocytes at the early stages of activation. We report that the majority of cells binding to thrombin-activated endothelial cells from a peripheral blood mononuclear cell (PBMC) preparation are monocytes. The adhesion of PBMC to thrombin-activated, but not resting, endothelial cells was inhibited (66%) by a monoclonal antibody (mAb) directed against alpha v beta 3. Elutriated monocytes or a monocytic cell line (U937) were also inhibited by this antibody, its F(ab)'2 fragments and three other anti-(alpha v beta 3) mAbs. alpha v beta 3 isolated from endothelial-cell lysates significantly inhibited the adhesion of monocytes and U937 cells to endothelial cells. A peptide motif (RGDF) known to interact with alpha v beta 3 inhibited U937 cell adhesion to activated endothelial cells by 53%. Finally, an anti-(P-selectin) mAb (LYP20) or a platelet-activating factor (PAF)-receptor antagonist (WEB 2086) inhibited monocyte adhesion to activated endothelial cells. This study shows for the first time that alpha v beta 3 is implicated, in addition to P-selectin and PAF, in the adhesion of monocytes to activated endothelial cells.
Amino Acid Sequence↗
Interleukin 13 is a B cell stimulating factor.
The recently cloned human interleukin 13 (IL-13) is a novel cytokine expressed in activated T cells that has been shown to inhibit inflammatory cytokine production by lipopolysaccharide-activated monocytes. The protein encoded by the IL-13 cDNA is the human homologue of a mouse Th2-product called P600. Here, we show that IL-13 acts at different stages of the B cell maturation pathway: (a) it enhances the expression of CD23/Fc epsilon RII and class II MHC antigens on resting B cells; (b) it stimulates B cell proliferation in combination with anti-Ig and anti-CD40 antibodies; and (c) it induces IgE synthesis. Thus, the spectrum of the biological activities of IL-13 on B cells largely overlaps that previously ascribed to IL-4. The present observations suggest that IL-13 may be an important factor, in addition to IL-4, in the development of allergic diseases.
B-Lymphocytes↗
Towards identification of memory B cells in human tonsils.
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B-Lymphocyte Subsets↗
Moabs MAS516 and 5B5, two fibroblast markers, recognize human follicular dendritic cells.
Follicular dendritic cells (FDC) are only located within follicles of secondary lymphoid tissues. The origin of this peculiar cell type is not clearly defined. To contribute to this study, we applied two monoclonal antibodies (MAS516 and 5B5) considered as specific for fibroblasts to tonsil cryosections and to isolated follicular dendritic cells. On the basis of an enzyme cocktail digestion of human tonsils and a fractionation procedure on albumin gradients, FDC can be prepared in the form of cell aggregates with associated lymphoid cells. MAS516 reacts with surface membrane molecules expressed by human fibroblasts, tissue macrophages and peripheral blood monocytes. With immunoperoxidase assays on tonsil cryosections connective tissue cells and macrophages are stained. Inside germinal centres, heavy labelling of the light zone was found. The MAS516 staining pattern is very similar to that of specific FDC markers DRC-1 or BU10. All isolated FDC reacted with MAS516 antibody. 5B5, considered as a typical fibroblast marker, reacts with human prolyl-4-hydroxylase which is an intracellular enzyme related to collagen biosynthesis. In cryosections, interfollicular and capsular areas showed 5B5 positive connective tissue fibroblasts. In germinal centres, some cells presenting features of FDC were 5B5 positive. After cell separation, 25%-50% of the isolated FDC were labelled with this antibody. This positivity of some FDC for 5B5 antibody may support the idea of their fibroblastic origin. The combination of observations realized in situ and after cell purification ensured an unequivocal recognition and identification of FDC.(ABSTRACT TRUNCATED AT 250 WORDS)
Antibodies, Monoclonal↗
Phenotypic and functional heterogeneity of the IgD- B cell compartment: identification of two major tonsillar B cell subsets.
Two major B cell subpopulations were identified in the IgD- compartment of tonsils and subsequently isolated. They displayed the following phenotypes: CD10+CD38+CD44- (CD38+ B cells) and CD10-CD38-CD44+ (CD38- B cells). Of the CD38- B cells, 70% also expressed CD24 and CD39, whereas CD77 was specifically distributed on 40% of CD38+ B cells, suggesting an additional level of heterogeneity in the cellular composition of these two B cell types. Whereas the majority of CD38+ B cells were in cycle, most CD38- B cells were quiescent. Conversely, Bcl-2 was expressed in CD38- B cells but was not detected in CD38+ B cells. Of the CD38- B cells, 30% bore the homing receptor Leu-8/Mel-14, whereas CD38+ B cells lacked this marker. Thus, CD38- B cells have both survival capacity and migratory competence. Both subsets expressed surface (s) Igs which were mainly of the IgG class, implying that most of these cells have already undergone isotype switching. CD38- B cells proliferated vigorously and produced large amounts of IgG in response to cytokines, following ligation of slgs or CD40. In contrast, CD38+ B cells were only stimulated for DNA synthesis by a combination of IL-4 and anti-CD40 antibodies, and failed to differentiate into Ig-secreting cells regardless of the stimulus applied. We propose that CD38- B cells represent an extra-follicular mature B cell population which has been positively selected and rescued from apoptosis, whereas the CD38+ B cell subset is composed of germinal centre B cells.
ADP-ribosyl Cyclase↗
Responsiveness of chronic lymphocytic leukemia B cells activated via surface Igs or CD40 to B-cell tropic factors.
Recent studies performed in the laboratory have established that interleukin-4 (IL-4) used in combination with anti-CD40 monoclonal antibody (MoAb) 89 presented on Ltk- mouse fibroblasts stably expressing human Fc gamma RII/CDw32 (referred to as the CD40 system) sustains long-term proliferation of normal human B cells. In the present study, B-cell chronic lymphocytic leukemias (B-CLLs) activated through slgs or CD40 were examined for their capacity to proliferate and differentiate in response to various cytokines. Our results indicate that the outcome of IL-4 stimulation on the in vitro growth of B-CLL depends on the signalling pathway used for their activation. Whereas IL-4 did not display any growth-stimulatory effect on B-CLL activated by Ig cross-linking agents, it could stimulate DNA synthesis and enhance the viable cell recovery when leukemic B cells were cultured in the CD40 system. Most B-CLL samples were induced for IgM synthesis upon Staphylococcus aureus strain Cowan I stimulation. This Ig response was potentiated by IL-2 and antagonized by IL-4. Anti-CD40 MoAb used alone or in combination with cytokines (IL-1 alpha to IL-6, interferon gamma, tumor necrosis factor gamma, and transforming growth factor beta) failed to induce Ig secretion from B-CLL cells. No evidence for Ig isotype switching was obtained with the cytokines listed above, regardless of the mode of activation. Taken together, our results suggest that B-CLL cells can be partially released from their apparent maturation block by IL-2 and Ig cross-linking agents. In contrast, combinations of IL-4 and cross-linked anti-CD40 antibodies induced entry of B-CLL cell into cycle, but poorly stimulated their differentiation into Ig secreting cells.
Adult↗
Interleukin 10 is a potent growth and differentiation factor for activated human B lymphocytes.
Interleukin 10 (IL-10), originally identified as a TH2 helper T-cell product able to inhibit cytokine production by TH1 cells, is highly homologous to BCRF1 (viral IL-10), an open reading frame in the Epstein-Barr virus genome. Here, we show that human and viral IL-10 stimulate DNA replication of B lymphocytes activated either via their antigen receptor or via their CD40 antigen. IL-4 and IL-10 display additive effects and induce a strong increase in the number of viable cells. Moreover, IL-10 induces activated B cells to secrete large amounts of IgG, IgA, and IgM, and the combination of IL-10 and IL-4 results in the secretion of the four immunoglobulin isotypes. Thus, IL-10 may play an important role in the amplification of humoral responses.
Antibody Formation↗
Interleukin 10 and transforming growth factor beta cooperate to induce anti-CD40-activated naive human B cells to secrete immunoglobulin A.
In the present report, we have investigated the in vitro differentiation of surface(s) sIgD+ and sIgD- human B cells into Ig-secreting cells in response to various stimuli. sIgD+ B cells homogeneously expressed some of the antigens identifying mantle zone B cells, but lacked expression of germinal center markers, thus confirming that the B cell populations positively selected on the basis of sIgD expression were highly enriched for naive B lymphocytes. Conversely, sIgD- B cells expressed some of the antigens specifically associated with germinal center B cells. T cell-independent differentiation of sIgD+ and sIgD- B cells could be achieved by simultaneous crosslinking of sIgs and CD40 in the presence of a mouse Ltk- cell line stably expressing human CDw32/Fc gamma RII (CDw32 L cells). In this experimental system, sIgD+ B cells were exclusively proned for IgM synthesis, whereas sIgD- B cells produced IgG, IgM, and IgA. Both the human and viral forms of interleukin 10 (IL-10) strongly increased the Ig secretion by sIgD+ and sIgD- B cells simultaneously activated through sIgs and CD40. IgM and IgG constituted the predominant Ig isotype produced by sIgD+ and sIgD- B cells, respectively, in response to IL-10. sIgD+ B cells could be induced for IgA synthesis upon co-culturing with transforming growth factor beta (TGF-beta) and IL-10, in the presence of an anti-CD40 monoclonal antibody presented by the CDw32 L cells. In contrast, TGF-beta suppressed the IL-10-mediated IgG, IgM, and IgA secretions by sIgD- B cells. sIgD+ B cells could not be induced for IgA synthesis by TGF-beta and IL-10 after crosslinking of their sIgs, suggesting that ligation of CD40 was one of the obligatory signals required for commitment of naive B cells to IgA secretion. Limiting dilution experiments indicated that the IgA-potentiating effect of TGF-beta was due to its capacity to increase the frequency of IgA-producing cells, most likely as a consequence of class switching. Taken together, our data strongly suggest that TGF-beta is involved in the regulation of IgA isotype selection in humans.
Antibody-Producing Cells↗
Antiproliferative effects of interleukin-4 on freshly isolated non-Hodgkin malignant B-lymphoma cells.
The pattern of in vitro growth response of freshly isolated non-Hodgkin malignant lymphoma B cells (NHML) to cytokines was investigated. Ten tumor specimens of low- or intermediate-grade malignancy were selected for study. To assess their proliferative capacity in vitro, B-lymphoma cells were activated through ligation of their surface Ig receptor with insolubilized anti-IgM antibodies or Staphylococcus aureus strain Cowan I (SAC). In the great majority of cases, interleukin-2 (IL-2) was the sole factor that significantly and reproducibly stimulated DNA synthesis in NHML activated through their surface Igs. Other B-cell tropic factors, including IL-4, IL-5, IL-6, and tumor necrosis factor-alpha (TNF-alpha), failed to elicit a growth response in most of the IL-2-responsive neoplastic samples. However, one specimen among 10 exhibited the opposite pattern of response and proliferated following culture with IL-4 and anti-Ig reagents, but not after IL-2 stimulation. Three specimens could also be induced for DNA synthesis on cross-linking of their surface Igs in the absence of exogenous growth factors. Although IL-4 could not support the in vitro growth of the majority of NHML cases, it strongly suppressed the proliferative signals delivered to these cells by anti-Ig reagents used alone or in combination with IL-2. Our data suggest that, in most cases, IL-4 essentially provides growth-inhibitory signals to NHML when they are activated through their surface Ig receptors and as such may be considered to be a valid candidate for future therapy of this type of mature B-cell malignancy.
Antibodies, Anti-Idiotypic↗
Proliferation and differentiation of human CD5+ and CD5- B cell subsets activated through their antigen receptors or CD40 antigens.
The pan-T cell antigen CD5 has been shown to delineate two different mouse B cell subsets, originating from distinct progenitors. In man, on average, 30% of the tonsillar B cell pool expresses this antigen. In the present report, a detailed comparison of the CD5+ and CD5- B cell response to cytokines, following activation via surface immunoglobulins (sIg) or CD40 antigen, was undertaken. CD5+ B cells were positively selected by panning or by sorting from tonsils. Two-color immunofluorescence analysis performed on tonsillar B cell populations showed that CD5+ B cells displayed most of the phenotypic features of mantle zone B cells. CD5+ B cells could be stimulated for DNA synthesis by mitogenic concentrations of Staphylococcus aureus, Cowan I strain (SAC), insolubilized anti-IgM antibodies, immobilized anti-CD40 antibodies and phorbol 12-myristate 13-acetate (PMA). The growth-response of small dense CD5- B cells to these T cell-independent mitogens was comparable to that of CD5+ B cells, whereas the low-density, in vivo-activated, CD5- B cells were only marginally stimulated by Ig-cross-linking agents and PMA. Following ligation of sIg, both B cell subsets proliferated essentially in response to interleukin (IL)-2 and IL-4. When used in co-stimulation with immobilized anti-CD40 antibodies, IL-4 promoted growth of CD5+ and CD5- B cells, whereas IL-2 displayed only moderate stimulatory effects. CD5+ and CD5- B cells differentiated into Ig-secreting cells when they were co-cultured with SAC or cross-linked anti-CD40 antibodies and IL-2. However, IgM constituted the major component of the Ig response of CD5+ B cells, whereas high levels of IgG were secreted by CD5- B cells.
Antigens, CD↗
Growth factor requirements for the stimulation of germinal center B cells: evidence for an IL-2-dependent pathway of development.
Germinal center (GC) B cells readily undergo apoptosis, a tendency which can be suppressed in vitro by immobilized anti-Ig; mAb to CD40 and soluble CD23 (in synergy with IL-1 alpha) also effect rescue of GC cells from programmed cell death. In the present study, the signals which stimulate rescued GC populations to DNA synthesis have been examined and compared to those established for the activation of follicular mantle (FM) B cells. On co-culture with anti-Ig, optimal responses in FM B cells can be achieved with a combination of IL-4 and CD40 antibody; these activities also provided a modest stimulus to GC cells but, for this population, anti-Ig was ineffective at augmenting the response further. Stimulations of GC B cells were enhanced, however, when performed on a support of primary fetal lung fibroblasts; a major influence of stroma was to promote, by direct cell-cell contact, the CD40-dependent survival of GC B cells. FM B cells were relatively independent of such stromal support. In marked contrast to FM cells, GC B cells were found to respond by enhanced DNA synthesis to IL-2 even when quite low concentrations of the factor were present (IC50 = 2 U/ml). Stimulation of GC cells via this pathway was augmented almost 2-fold on the inclusion of anti-Ig whereas neither fibroblasts, IL-4, nor CD40 antibody made any additional contribution to the IL-2-dependent response. The requirements found for stimulating GC cells in vitro are discussed with reference to the signals that this population may encounter in appropriate microenvironments in vivo: the variety of options apparently available could reflect changing priorities at different stages of a developing GC response.
Antigens, CD↗
Human interleukin 4.
Human IL-4 is a mature 129 AA glycoprotein, mostly secreted by activated T cells. It is a pleiotropic cytokine which acts on T and B lymphocytes, monocytes, polymorphonuclear cells, fibroblasts and endothelial cells. In addition it acts at various stages of cell differentiation and its effects are also dependent on the cytokine environment. In particular, IL-4 blocks some of the effects of IL-2 whereas interferon gamma blocks some of the effects of IL-4. In vitro and in vivo experiments in mouse and in vitro experiments in man have shown that IL-4 plays a crucial role in the induction of IgE production, whereas interferons counteract this effect. Human IL-4 binds to a high affinity receptor which is composed at least of one 130-kDa glycoprotein of 800 AA, a member of the newly described hematopoietin receptor superfamily. IL-4 may prove useful as an antitumoral and antiinflammatory agent.
Animals↗
Human interleukin 4 down-regulates the surface expression of CD5 on normal and leukemic B cells.
CD5 is a pan-T cell antigen which is expressed on a minor subset of normal B lymphocytes and on most chronic lymphocytic leukemia B cells (B-CLL). In this study, it is demonstrated that interleukin (IL) 4 down-regulates the surface expression of CD5 on tonsil B cells and B-CLL cells, but not on T cells. IL 4 inhibits both the spontaneous and the phorbol myristate acetate (PMA)-induced hyperexpression of CD5 on tonsil B cells. In contrast, IL 4 only suppresses the PMA-induced hyperexpression of CD5 on B-CLL, whereas the spontaneous CD5 expression is essentially unaffected. The IL 4 concentrations required to down-regulate CD5 are the same as those required to up-regulate CD23. The IL 4-mediated down-regulation of CD5 is an intrinsic property of this IL, since an anti-IL 4-neutralizing antiserum blocks this effect. Interferon (IFN)-gamma, which inhibits the IL 4 induced CD23 expression, does not block the IL 4-induced down-regulation of CD5. Recombinant IL 1 alpha, IL 2, IL 3, IL 5, IL 6, tumor necrosis factor (TNF)-alpha, IFN-gamma and granulocyte macrophage colony-stimulating factor neither inhibit nor stimulate CD5 expression on B cells, therefore suggesting that the capacity to down-regulate CD5 expression on B cells is specific to IL 4.
Antigens, Differentiation↗
Interleukin (IL) 4 counteracts the helper effect of IL2 on antigen-activated human B cells.
We tested the effect of interleukin (IL) 4 on the specific IgM antibody response induced by trinitrophenylated-polyacrylamide beads (TNP-PAA) in cultures of human B cells. T cell help was provided by exogeneous IL2. IL4 profoundly suppressed the response to optimal concentrations (50 U/ml) of IL2, with a 50% inhibitory concentration of 6 U/ml. This was due neither to a shift in the kinetics nor to a switch to an IgG response. The production of anti-TNP antibody (as measured by an enzyme-linked immunosorbent assay in the culture supernatant) was inhibited to the same extent as the generation of plaque-forming cells. The effect of IL4 was completely abolished by a neutralizing antibody toward IL4. Kinetic studies showed that IL4 had to be present during the first 48 h of culture to fully inhibit the response. The sequential stimulation of B cells by antigen and by IL2 showed that IL4 does not negatively interfere with signaling through membrane Ig but counteracts the effect of IL2 on antigen-activated B cells.
Antibody Formation↗
Activation of human B lymphocytes through CD40 and interleukin 4.
We have produced and characterized a new CD40 monoclonal antibody, mAb 89, which in the presence of anti-IgM antibodies co-stimulates to induce B cell proliferation. mAb 89 activates resting B cells as shown by an increase in cell volume and an enhanced subsequent proliferation of B cells in response to anti-IgM antibody. However, mAb 89 does not prepare B cells to respond to the growth-promoting activity of interleukin (IL) 2 or IL 4. Unlike IL 2 and IL 4, mAb 89 only weakly stimulates the proliferation of anti-IgM pre-activated B cells. Thus, the activating properties of anti-CD40 are likely to explain its co-stimulatory effect on B cells. Interestingly, the anti-CD40 mAb 89 was found to act in synergy with IL 4, but not with IL 2, in co-stimulation and restimulation assays. In this respect, anti-CD40 does not induce a significant increase of B cell surface IL 4 receptors while IL 4, but not IL 2, induces a twofold increase of the CD40 antigen expression. Thus the synergistic interaction between IL 4 and anti-CD40 may be related to the IL 4-dependent increase of CD40 antigen expression.
Antibodies, Monoclonal↗
Analysis of the B-cell growth-promoting activity of human IL-4, the co-stimulatory assay with anti-immunoglobulin antibodies. Comparison with the B-cell growth-promoting activity of other lymphokines.
Human recombinant interleukin-4 (rIL-4) was assessed for its ability to promote the proliferative response of purified human B cells co-stimulated with submitogenic concentrations of soluble F(ab')2 fragments of anti-immunoglobulin (Ig) antibodies. The growth-promoting activity of rIL-4 was usually as potent as, or even more potent than, that of recombinant interleukin-2 (rIL-2), and more potent than that of recombinant interferon-gamma (rIFN-gamma). Preincubation with rIL-4 did not cause enhancement of the proliferative response of B cells to the subsequent addition of rIL-4 and anti-IgM antibody. In contrast, the proliferative response of B cells preincubated with anti-IgM antibody and rIL-4 was potentiated by the subsequent addition of rIL-4. The simultaneous addition of rIFN-gamma and rIL-2 or rIFN-gamma and rIL-4 had an additive effect in comparison with the response induced by rIL-2 or rIL-4 alone, respectively, whereas simultaneous addition of rIL-2 and rIL-4 induced a response equal or lower than that stimulated by rIL-2 or rIL-4 alone. The addition of rIFN-gamma at the beginning of culture or preincubation of B cells with rIFN-gamma and anti-IgM antibody potentiated the proliferative response of B cells to the subsequent addition of either rIL-2 or rIL-4. Taken together, these data suggest that rIL-4 acts as a growth factor for activated human B cells and displays on such cells a growth-promoting activity similar to that of rIL-2.
Adjuvants, Immunologic↗