Cell‐mediated cytotoxicity to trinitrophenyl‐modified syngeneic lymphocytes

Abstract Spleen cells from B10 congenic mouse strains were cultured in vitro by a modification of the Mishell‐Dutton technique with trinitrophenyl (TNP)‐modified syngeneic spleen cells. Five days later, the effector cells generated were incubated with 51 Cr‐labeled unmodified or TNP‐modified spleen or tumor target cells, and the percentage of specific lysis determined. The results obtained using modified syngeneic as well as congenic target cells indicated that although TNP‐modification of the target cells was necessary to obtain lysis, the cytotoxicity was not specific for TNP exclusively, but was primarily directed against modified syngeneic cell surface components which may or may not have included the TNP moiety as an integral part of the recognition unit. A number of criteria were used to demonstrate that the phenomenon was attributed to T cell‐mediated cytotoxicity, and was not due to lymphocyte‐dependent antibody (LDA). These included: (a) failure of TNP‐lysine to block the effector phase; (b) lack of detectable LDA in the culture media; (c) failure of spleen cells from athymic nude donors to generate effector cells; (d) sensitivity of effector cells to rabbit anti‐mouse brain serum; and (e) the generation of effector cells by cortisone‐resistant thymocytes. The specificity observed between the syngeneic TNP‐modified sensitizing and target cells is compatible with the hypothesis that the TNP is altering cell surface proteins which are controlled by genes within distinct regions of the H‐2 major histocompatibility complex, and that these proteins are conformationally changed so as to be immunogenic to syngeneic thymus‐derived lymphocytes.