SPECIFIC TARGET CELL LYSIS BY SUPERNATANTS DERIVED FROM ALLOIMMUNE MURINE CYTOTOXIC T LYMPHOCYTES: POSSIBLE ROLE OF A LYMPHOTOXIN-T CELL RECEPTOR COMPLEX

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ABSTRACT Lymphocytes or purified T cells obtained from spleens or peritoneal exudate (PEL) of alloimmune C57B1/6 or BALB/c mice, when placed on monolayers of lectin (PHA) coated allogeneic fibroblasts, rapidly release (6–8 hr) into the supernatant antigen specific cell lytic material(s). These supernatants could induce rapid (10 hr) and specific lysis of the sensitizing allogeneic target cells during in vitro 51 Cr release assays. Analysis of the lytic supernatant revealed the following properties: a) antisera which could neutralize murine lymphotoxin (LT) activity in vitro could inhibit this effect; b) absorption of supernatants on the specific target cells at 4°C removed both the specific lytic activity and nonspecific LT activity detectable on L-929 cells in vitro ; c) polyspecific goat anti mouse Ig sera had no effect on this lytic activity, and removal of T cells by anti θ serum + C’ removed the capacity of the remaining cells to release these materials; and d) this material(s) was highly unstable. Furthermore, biochemical fractionation of lytic supernatants by molecular sieving revealed the specific cell lytic activity eluted in the void volume or in the region of the high MW LT complex. Because the lytic effects could not be shown to be due to classical Ab + C', and since purified alloimmune T lymphocytes yielded the most active supernatants, we feel the data is consistent with the concept that the short-lived specific cell lytic material in these supernatants is a high MW complex containing LT or LT-like molecules in functional association with specific T cell antigen binding receptor (s) molecules.