INDUCTION OF LYT-2(-LYMPHOCYTES FOLLOWING PRIMARY AND SECONDARY SALMONELLA INFECTION() CYTOTOXIC T)

Investigations of the cytotoxic activity of T cells induced following one or two intraperitoneal doses of live Salmonella revealed that cyto toxicity was restricted to the Lyt-2(+) T-cell subset and was enhanced following secondary infection with Salmonella. Initial studies using the lectin-dependent cellular cytotoxicity (LDCC) assay detected Lyt-2 (+) C cytotoxic T cells in peritoneal cell suspensions of S. enteritid is 11RX (11RX)-infected mice, with the peak of activity occurring 5 da ys after infection. This did not correlate with the proliferative acti vity of these cells, which peaked 10-12 days after infection. Secondar y challenge with 11RX or S. typhimurium C5 (C5) induced a rapid increa se in the cytotoxic activity of Lyt-2(+) peritoneal T cells and was de tected even 21 days later. The antigen specificity of some of these ce lls was confirmed in cytotoxicity assays using P815 tumour cells infec ted with 11RX organisms as targets. No cytotoxic activity was detected in the spleen cell suspensions of infected (and normal) mice unless t he cells were first activated by in vitro culture with concanavalin A (Con A). Both types of activated spleen cells showed LDCC but Salmonel la-specific cytotoxic Lyt-2(+) T cells were detected only in spleen ce ll (SC) cultures prepared from mice challenged with a second dose of S almonella.