Destruction of Human Lymphoid Tissue-Culture Cell Lines by Human Peripheral Lymphocytes in 51Cr-Release Cellular Cytotoxicity Assays2

Abstract

5ICr-release assay showed that peripheral blood lymphocytes from all of 21 normal individuals had cell-mediated cytotoxic reactivity against several human lymphoid tissue-culture cell lines. Lysis by the normal donor lymphocytes of the various cell lines varied markedly among lines; lysis of a given cell line by an individual's lymphocytes also varied at different times. For example, human lymphoid cell lines, including F-230, F-265, and Raji, were destroyed by lymphocytes of all individuals tested. Other lines including SS-5 and NC-37 were lysed by lymphocytes from most, but not all, normal donors. Finally, cell lines S5-4 and Stuck were not destroyed by lymphocytes from any normal donors tested, or their antigenicity fluctuated from positive to negative at different times. Lymphocytes of 9 of 13 individuals had significant cytotoxic reactivity against established autologous lymphoid cell lines. Lysis by lymphocytes from immunodeficient patients and patients receiving immunosuppressive drugs was less than that by lymphocytes from normal individuals. Agents such as X-irradiation, actinomycin D, 3′ ,5′-cyclic AMP, and concanavalin A completely or partially blocked the cytolytic activity of lymphocytes against F-265 cells. Target cell inhibition tests revealed that addition of graded doses of unlabeled F-265 cells always inhibited the release of 5lCr from labeled F-265 cells. Similarly, cytotoxicity of F-265 was inhibited by some other cultured lymphoid cells, including NC-37, but was not inhibited by at least one other cultured lymphoid cell line (Stuck). Normal human lymphocytes stimulated in vitro by phytohemagglutinin (PHA) did not inhibit lysis of F-265, nor were they directly lysed by lymphocytes of normal individuals. F-265 cells grown in media containing human serum instead of fetal bovine serum (FBS) were effective targets in the assay. The results suggested that true cell-mediated immunologic reactions caused the lysis of human tissue-cultured lymphoid cells by normal donor lymphocytes. The relevant antigen(s) appeared to be neither associated with or possessed by PHA-stimulated lymphocytes nor related to antigens of FBS, but may be antigen(s) expressed by lymphocytes in prolonged tissue culture.