UC Irvine

This report describes the in vitro inhibition of several classes of human lymphocyte-mediated lysis by antisera from mice and rats immunized with concanavalin A-stimulated human T-enriched lymphocytes. The inhibitory antibodies in these antisera recognized molecules on the surface of cytotoxic lymphocytes, and did not bind to B-cell lines. Experiments were performed to demonstrate that these antisera were not inhibiting cytolysis by trivial mechanisms such as (i) masking of target cell antigens by anti-target cell antibodies, (ii) agglutinating effector cells, thereby preventing effector-target cell contact, or (iii) toxicity to the effector cells. Dextran dispersion experiments revealed that these antisera inhibit the post-conjugate formation phase of cytolysis mediated by cytotoxic T lymphocytes. These antisera inhibited natural killer-like cytotoxicity and lectin-dependent cell-mediated cytotoxicity as well as lysis mediated by both mixed cell culture-generated cytotoxic T lymphocytes and cytotoxic T-lymphocyte cell lines. These findings suggest that these in vitro systems of cell-mediated lysis may share a common step; however the different classes of cytolysis may have been inhibited by separate antibodies in the antisera. This rapid reproducible method of generating inhibitory antisera will facilitate the study of the molecules involved in the post-conjugate formation phase of human cytotoxic T-lymphocyte-mediated lysis. © 1982.