title: Down-regulation of T-cell proliferation in response to soluble anti-CD3 antibodies through development of redirected cytolytic activity eliminating costimulatory cells.
abstract: CD4+ T-depleted spleen cells (CD8+ T cells) activated by anti-CD3 antibodies (aCD3) suppressed proliferation of CD8+ T-depleted spleen cells (CD4+ T cells) and fresh normal T cells in response to aCD3. Antigen-nonspecific cytolytic activity was induced in splenic CD8+ T cells by stimulation with aCD3 and showed the peak level on day 3, whereas cytolytic activity induced in CD4+ T cells was weak. Intact Ig but not F(ab')2 of aCD3 induced and mediated cytolytic activity. Correspondingly the cytolytic activity induced by aCD3 was directed against target cells bearing Ig-binding Fc-receptor activity and cytolysis was inhibited by the addition of free Ig into the assay system. We showed that aCD3-activated T cells carried a high level of aCD3 on their surface at the time after the peak proliferation when they attained high cytolytic activity. This raised the possibility that the anti-CD3-induced aCD3-redirected cytolytic activity eliminated Fc-receptor-bearing costimulatory cells in the culture for down-regulation of the T-cell proliferation. This view was supported by partial restoration of anti-CD3-induced low responsiveness of CD8+ T cells by the addition of fresh costimulatory cells. These results suggested a new pathway of down-regulation of T-cell proliferation by aCD3-activated cytolytic CD8+ T cells.
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic; D015536:Down-Regulation; D051379:Mice; D008807:Mice, Inbred BALB C; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000906:Antibodies; D017252:CD3 Complex