title: Early events in lymphocyte activation as defined by three new monoclonal antibodies.
abstract: Three new lymphocyte activation antigens are described whose kinetics of appearance place them very early in the activation pathway. The 78,000 dalton early antigen (Ea) 1 is present at low levels on resting lymphocytes, and its expression is enhanced twofold to threefold within 3 hr of stimulation. Ea2, a nondisulfide-bonded 86,000 and 73,000 dalton heterodimer, is first detectable 3 hr after activation and peaks by 9 hr. Its presence on all but a few cell lines, plus the variable association with a lower m.w. (28,000) structure, suggest that it may serve as a receptor for a growth factor. Neither Ea1 nor Ea2 are restricted to lymphocytes. The 31,000 dalton Ea3 antigen is induced only by PHA but not by other means of activation, and may pre-exist within the cell. The Ea3 antibody blocks PHA-induced but not OKT3-induced mitogenesis, suggesting differences in the pathways of activation by these two stimuli. These reagents, and OKT3, were used to define the cyclosporine A (CSA)-sensitive stage of lymphocyte activation. CSA blocks at a point before the biosynthesis of Ea1 and after that of T3/T cell receptor loss from the cell surface, at a point close to Ea2 biosynthesis.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000276:immunology*; D003208:Concanavalin A / Q000494:pharmacology; D003524:Cyclosporins / Q000494:pharmacology; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D007700:Kinetics; D008213:Lymphocyte Activation / Q000187:drug effects; D008214:Lymphocytes / Q000276:immunology*; D051379:Mice; D010835:Phytohemagglutinins / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D003524:Cyclosporins; D007376:Interleukin-2; D010835:Phytohemagglutinins; D003208:Concanavalin A