title: Studies on T lymphocyte activation. I. Requirements for the mitogen-dependent production of T cell growth factors.
abstract: Conditioned media (CM) obtained from concanavalin A (Con A)-stimulated spleen cell cultures maintain mitogen-derived T cell blasts in exponential growth for indefinite periods of time. Such purified T cell blasts do not respond to Con A, and the growth-promoting activity in CM is independent of the mitogenic lectin used for its production. However, the appearance of activity in CM is Con A dose-dependent. Furthermore, the production of these T cell growth factors is independent of B cells, while it requires both T cells and nontheta-bearing, probably Ia-positive cells present in normal and nude spleens. On the other hand, the T cell blasts which are reactive to the growth factors, neither produce CM by themselves nor can they cooperate with nude spleen cells for its production, in the presence of a mitogenic lectin. Since the concentration of growth factors in CM determines the extent of T cell growth, we propose that the growth of some T cells is necessarily dependent upon the activity in CM described here and, consequently, that the basis for T cell activation is the induction of such growth factors.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D003208:Concanavalin A / Q000494:pharmacology; D003470:Culture Media; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D006133:Growth Substances / Q000096:biosynthesis*; D006649:Histocompatibility Antigens; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008819:Mice, Nude; D008934:Mitogens / Q000494:pharmacology*; D051381:Rats; D011914:Rats, Inbred BN; D011917:Rats, Inbred Lew; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D003470:Culture Media; D006133:Growth Substances; D006649:Histocompatibility Antigens; D008934:Mitogens; D003208:Concanavalin A