IL-4-producing CD8+ T cell clones can provide B cell help.
Interactions between CD4+ T cells and B cells are mediated by both soluble factors and cell surface molecules. The Ag-independent interaction between the CD40 ligand, expressed on activated T cells, and its CD40 receptor, expressed on B cells, enhances B cell proliferation in response to IL-4 stimulation. The expression of the CD40 ligand is induced on CD4+ T cells by stimulation with Ag-pulsed APC or mitogens. Here, we show that at least some IL-4-producing murine CD8+ T cell clones can be induced to express the CD40 ligand when stimulated with anti-CD3 mAb. Additionally, such activated CD8+ IL-4-producing clones potentiate the proliferative response of small resting B cells to IL-4 and induce Ig secretion by small resting B cells to IL-4 and IL-5. Proliferation of small resting B cells cultured with IL-4 in the presence of activated IL-4-producing CD8+ murine T cell clones appeared to be mediated by the expression of the CD40 ligand on the T cell because an anti-CD40 ligand mAb inhibited this proliferative response. A conventional murine CD8+ CTL clone, which did not produce IL-4 or express CD40 ligand upon activation, did not potentiate proliferation of small resting B cells exposed to IL-4. Thus, under some circumstances, CD8+ T cells that are able to express CD40 ligand may be able to provide B cell help.
Cronin
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Committee on Immunology, University of Chicago, IL 60637.
Stack
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R
Fitch
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FW
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D017252:CD3 Complex / Q000276:immunology; D023201:CD40 Ligand; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002999:Clone Cells; D003601:Cytotoxicity Tests, Immunologic; D005260:Female; D005434:Flow Cytometry; D015847:Interleukin-4 / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000276:immunology; D008211:Lymphocyte Cooperation / Q000276:immunology*; D008222:Lymphokines / Q000032:analysis; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008815:Mice, Inbred Strains; D011948:Receptors, Antigen, T-Cell / Q000276:immunology
D017252:CD3 Complex; D008222:Lymphokines; D008562:Membrane Glycoproteins; D011948:Receptors, Antigen, T-Cell; D023201:CD40 Ligand; D015847:Interleukin-4