Inhibition of T cell cytolytic potential by concanavalin A: a result of activation?
We investigated the effects of concanavalin A (Con A) on T cell-mediated lympholysis. Human cytotoxic T cell lines were generated from peripheral blood and these lines were shown to lyse lectin-coated K562 target cells. Addition of soluble Con A to the assay resulted in a dose-dependent inhibition of the cytolysis. Preincubation experiments demonstrated that this inhibitory effect was exerted at the effector cell level. F(ab')2 fragments of WT32, a monoclonal antibody against T3, blocked the cytolysis of Con A-preincubated K562 target cells to a large extent. We further showed that Con A strongly inhibited the cytolysis exerted by alloantigen-specific, major histocompatibility complex (MHC)-restricted cytotoxic T cell lines against their specific targets. On the other hand, Con A had no clear inhibitory effect on the cytotoxicity of freshly isolated peripheral blood mononuclear cells against K562 target cells. We hypothesize that Con A-induced inhibition of cytotoxicity may be explained by a direct triggering of the lytic potential of activated T cells.
D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology; D002460:Cell Line; D003208:Concanavalin A / Q000494:pharmacology*; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects*; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects*
D000945:Antigens, Differentiation, T-Lymphocyte; D003208:Concanavalin A; D005947:Glucose