title: A second signal for T cell mitogenesis provided by monoclonal antibodies CD45 (T200).
abstract: The induction of T cell mitogenesis through CD3 is a complex process that requires at least two signals. The first one can be provided by Sepharose-bound CD3. The second one is normally provided by monocytes. The signal provided by Sepharose-bound CD3 is unable by itself to induce mitogenesis in monocyte highly depleted cells (MHDC). We describe here that the monoclonal antibody (mAb) 72-5D3 belonging to CD45 (T200), which was not mitogenic by itself, could replace monocytes when MHDC were activated by Sepharose-bound CD3. That is to say, in the absence of monocytes, mAb 72-5D3 gave a second signal necessary for T cell proliferation. Using eleven anti-CD45 mAb from other investigators we show that this effect is not a peculiar characteristic of 72-5D3 mAb. The effect of the mAb 72-5D3 was only effective in CD4-positive cells and was not observed when MHDC were activated with either soluble CD3 or concanavalin A. As both phorbol myristate acetate and mAb 72-5D3 can replace monocytes, a comparative study of their effects was undertaken. Phorbol myristate acetate but not mAb 72-5D3 induced proliferation of MHDC when recombinant interleukin 2 (rIL2) was added. On the other hand mAb 72-5D3 induced IL2 production in MHDC activated by Sepharose-bound CD3 and increased the IL2 production in Sepharose-bound CD3-activated peripheral blood mononuclear cells. In conclusion, data presented in this report indicate that the T200 molecule could be involved in T cell proliferation by giving a signal that induces the production of IL2 and bypasses the necessity of monocytes.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D002478:Cells, Cultured; D006649:Histocompatibility Antigens / Q000276:immunology*; D007376:Interleukin-2 / Q000096:biosynthesis; D017493:Leukocyte Common Antigens; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D009000:Monocytes / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D006649:Histocompatibility Antigens; D007376:Interleukin-2; D017493:Leukocyte Common Antigens; D013755:Tetradecanoylphorbol Acetate