Studies on the mechanism of lymphocyte- mediated cytolysis. VIII. The use of con A to delineate a distinctive killer T cell subpopulation.
Alloimmune spleen cells (C57BL/6 anti P815), but not normal spleen cells, lyse syngeneic (EL4) target cells in the presence of Con A. Con A dependent cytotoxicity was mediated by T cells and required the continued presence of lectin. Cytolysis in the presence of a succinylated derivative was equivalent to that seen with the parent Con A molecule. In contrast to previous reports of Con A dependent cytolysis, however, we conclude that lysis is not primarily caused by directly cytotoxic T cells. The reasons for this conclusion are: 1. Removal of directly cytotoxic cells by adsorption on P815 monolayers did not alter the Con A dependent cytolysis of EL4 cells; 2. Populations in which no direct T killers were demonstrable (e.g., spleen cells harvested 5 days after alloimmunization) lysed both P815 and EL4 cells in the presence of Con A; and 3. Con A dependent cytolysis, but not direct cytotoxicity, could be induced by culturing normal C57BL/6 spleen cells for 4 days with a sonicated extract of P815 cells. We hypothesize that the cell "activated" to lyse targets in the presence of Con A is a T cell which has differentiated lytic potential following alloantigenic stimulation, but has either insufficient density or affinity of antigen receptors to serve as a directly cytotoxic cell. The role of Con A is viewed as 2-fold: i) to "bridge" killer and target cell, and ii) to "activate" the effector.
D000818:Animals; D002469:Cell Separation; D003208:Concanavalin A / Q000494:pharmacology*; D003601:Cytotoxicity Tests, Immunologic; D006649:Histocompatibility Antigens; D007111:Immunity, Cellular; D007519:Isoantigens; D051379:Mice; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D006649:Histocompatibility Antigens; D007519:Isoantigens; D003208:Concanavalin A