title: T-B cell interaction inhibits spontaneous apoptosis of mature lymphocytes in Bcl-2-deficient mice.
abstract: Bcl-2 expression is tightly regulated during lymphocyte development. Mature lymphocytes in Bcl-2-deficient mice show accelerated spontaneous apoptosis in vivo and in vitro. Stimulation of Bcl-2-deficient lymphocytes by anti-CD3 antibody inhibited the spontaneous apoptosis not only in T cells but also in B cells. The rescue of B cells was dependent on the presence of T cells, mainly through CD40L and interleukin (IL)-4. Furthermore, we generated Bcl-2-deficient mice transgenic for a T cell receptor or an immunoglobulin, both specific for chicken ovalbumin, to test for antigen-specific T-B cell interaction in the inhibition of the spontaneous apoptosis. The initial T cell activation by antigenic peptides presented by B cells suppressed apoptosis in T cells. Subsequently, T cells expressed CD40L and released ILs, leading to the protection of B cells from spontaneous apoptosis. These results suggest that the antiapoptotic signaling via CD40 or IL-4 may be largely independent of Bcl-2. Engagement of the Ig alone was not sufficient for the inhibition of B cell apoptosis. Thus, the physiological role of Bcl-2 in mature lymphocytes may be to protect cells from spontaneous apoptosis and to extend their lifespans to increase the opportunity for T cells and B cells to interact with each other and specific antigens in secondary lymphoid tissues. Bcl-2, however, appears to be dispensable for survival once mature lymphocytes are activated by antigen-specific T-B cell collaboration.
authors.affiliation: Howard Hughes Medical Institute, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: K
authors.initials: K
authors.lastname: Nakayama
authors.forename: K
authors.initials: K
authors.lastname: Nakayama
authors.forename: L B
authors.initials: LB
authors.lastname: Dustin
authors.forename: D Y
authors.initials: DY
authors.lastname: Loh
mesh_terms: D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000276:immunology*; D017252:CD3 Complex / Q000378:metabolism; D019013:CD40 Antigens / Q000378:metabolism; D002450:Cell Communication / Q000187:drug effects; D002478:Cells, Cultured; D005434:Flow Cytometry; D007136:Immunoglobulins / Q000235:genetics / Q000276:immunology; D015847:Interleukin-4 / Q000494:pharmacology; D051379:Mice; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D018448:Models, Immunological; D011518:Proto-Oncogene Proteins / Q000172:deficiency* / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D017252:CD3 Complex; D019013:CD40 Antigens; D007136:Immunoglobulins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011948:Receptors, Antigen, T-Cell; D015847:Interleukin-4