title: IgE production by normal human B cells induced by alloreactive T cell clones is mediated by IL-4 and suppressed by IFN-gamma.
abstract: Seven T cell clones were established from mixed leukocyte cultures in which PBMC from two healthy donors and from one patient suffering from the hyper-IgE syndrome were stimulated by the irradiated EBV-transformed B cell lines JY or UD53. Five of seven T cell clones, after activation by co-cultivation with JY or UD53 cells, induced a low degree of IgE production by normal blood B cells. In one experiment in which the normal B cells could activate the T cell clones directly, IgE production was also observed in the absence of the specific stimulator cells. IgE production was also obtained with supernatants of the T cell clones collected 4 to 5 days after activation by their specific stimulator cells. In addition, the supernatants induced IgG, IgA, and IgM synthesis. All seven clones produced variable concentrations of IL-4 and IFN-gamma. The clones FA-28 and BG-39, which failed to induce IgE synthesis, produced, compared with the other clones tested, relatively high quantities of IFN-gamma (4700 and 2500 pg/ml, respectively). These high levels of IFN-gamma accounted for the lack of induction of IgE synthesis, because in the presence of a polyclonal anti-IFN-gamma antiserum, supernatants of FA-10 and BG-39 induced significant IgE production. In addition, the low degree of IgE production induced by supernatants of two other T cell clones (FA28 and BG24) was 15- and 3-fold enhanced, respectively, in the presence of the anti-IFN-gamma antiserum. IgE synthesis by normal B cells was also induced by rIL-4, indicating that IL-4 present in T cell clone supernatants was responsible for induction of IgE production. This notion was supported by the finding that IgE production induced by supernatant of BG-24 was strongly inhibited by a polyclonal anti-IL-4 antiserum. In contrast, IgG and IgA production induced by supernatant of BG-24 were not significantly affected by the anti-IL-4 antiserum. Only a slight inhibition of IgM synthesis was observed. Collectively, our results indicate that both recombinant and naturally produced IL-4 induce normal human B cells to synthesize IgE. However, final IgE production induced by T cell clone supernatants is the net result of the inducing and suppressive effects of IL-4 and IFN-gamma respectively, that are secreted simultaneously by the T cell clones upon activation.
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D001402:B-Lymphocytes / Q000378:metabolism*; D001667:Binding, Competitive; D002474:Cell-Free System; D002999:Clone Cells / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology; D007073:Immunoglobulin E / Q000096:biosynthesis*; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007371:Interferon-gamma / Q000096:biosynthesis / Q000276:immunology / Q000494:pharmacology*; D015847:Interleukin-4; D007378:Interleukins / Q000096:biosynthesis / Q000276:immunology / Q000494:pharmacology*; D007958:Leukocyte Count; D008213:Lymphocyte Activation / Q000187:drug effects; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism
chemical_list: D000276:Adjuvants, Immunologic; D007106:Immune Sera; D007166:Immunosuppressive Agents; D007378:Interleukins; D011500:Protein Synthesis Inhibitors; D011994:Recombinant Proteins; D015847:Interleukin-4; D007073:Immunoglobulin E; D007371:Interferon-gamma