A new multivalent B cell activation model--anti-IgD bound to Fc gamma RI: properties and comparison with CD40L-mediated activation.
CHO cells permanently transfected with mouse Fc gamma RI alpha chain were prepared and used as a model to polyclonally activate murine B cells. The transfected CHO cells were treated with mitomycin C and placed into culture with varying quantities of anti-IgD. Using this model, murine splenic B cells (from BALB/c or C57Bl/6) were activated by mouse IgG2a-anti-IgD (10.4.22 or AF3.33) in a manner that is analogous to the activation of B cells seen with highly polyvalent anti-IgD (H delta(a)/1) prepared by chemical cross-linking to dextran. Efficient B cell activation was seen with nanogram quantities of anti-IgD. In the presence of IL-4 and IL-5, IgG1 production levels were equivalent to or better than seen when stimulation was with H delta(a)/1-dextran; however, IgE induction was not seen in either situation. The Ig production capacity was compared to that seen when B cells were activated with CD40L, using either CD40L-transfected CHO or a soluble CD40L construct. In the presence of IL-4 and IL-5, once a critical threshold of B cells was present, IgE and to a lesser extent IgG1 production was inversely proportional to B cell number when CD40L was the activating agent. In contrast, with Fc gamma RI-anti-IgD, IgM and IgG1 production was directly proportional to B cell number, while IgE production was never seen. Finally, when B cells were co-activated with immobilized anti-IgD and CD40L simultaneously, the IgE production from B cells induced by CD40L was strongly inhibited, while IgG1 and IgM production were not affected. Since B cell co-activation via sIg and CD40L would be a common scenario in secondary follicles, this inhibition of IgE production may be one of the reasons why serum IgE levels are much below IgG in normal immune situations.
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Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond 23298, USA.
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D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D019013:CD40 Antigens / Q000502:physiology*; D023201:CD40 Ligand; D016466:CHO Cells; D006224:Cricetinae; D016207:Cytokines / Q000502:physiology; D007072:Immunoglobulin D / Q000276:immunology*; D007141:Immunoglobulin Fc Fragments / Q000378:metabolism* / Q000502:physiology; D007136:Immunoglobulins / Q000096:biosynthesis / Q000378:metabolism; D008024:Ligands; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D018448:Models, Immunological; D017452:Receptors, IgG / Q000378:metabolism* / Q000502:physiology; D013154:Spleen / Q000166:cytology
D000888:Antibodies, Anti-Idiotypic; D019013:CD40 Antigens; D016207:Cytokines; D007072:Immunoglobulin D; D007141:Immunoglobulin Fc Fragments; D007136:Immunoglobulins; D008024:Ligands; D008562:Membrane Glycoproteins; D017452:Receptors, IgG; C039951:anti-IgD; D023201:CD40 Ligand