Isolation and partial characterizati4 on cloned cytotoxic T lymphocytes (cloned T cells/cell-surface antigens/lectins/y-interferon/glycoproteil

A small set of concanavalin A (Con A)-bind- ing glycoproteins was isolated from the surface membrane of cloned cytotoxic T lymphocytes (CTL) and partly identified using monoclonal antibodies. The binding of Con A by these glycoproteins on the CTL surface results in the secretion of y- interferon and in blocking the effector functions of the cells- namely, antigen-specific and lectin-dependent cytotoxicity. The Con A is evidently bound tightly to some surface struc- tures ("Con A-receptors") that are required for the activation and cytotoxic activity of CTL. To isolate and identify these receptors, antibodies to Con A were used. After Con A was allowed to bind to radiolabeled cloned CTL (labeled with 125I or (35S)methionine or 3H-labeled amino acids), the cells were washed thoroughly, lysed in detergents and anti-Con A anti- bodies were added to bind to the Con A-receptor complexes. The resulting aggregates were adsorbed with protein A-bear- ing Staphylococci and the receptors were then specifically re- leased from the pelleted bacteria by a-methyl-D-mannoside and analyzed by polyacrylamide gel electrophoresis under re- ducing conditions. Eight to nine labeled components were seen by autoradiography and with the aid of monoclonal antibodies to known T-cell surface molecules, four were identified as T200, lymphocyte function-associated antigen (LFA)-1, a- and jf-chains, and (on some clones) Lyt-2. Other components with Mr Y 160,000, 120,000, 46,000, 42,000, and 23,000 have not