Induction of Lyt-2+ cytotoxic T lymphocytes following primary and secondary Salmonella infection.

Investigations of the cytotoxic activity of T cells induced following one or two intraperitoneal doses of live Salmonella revealed that cytotoxicity 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+ cytotoxic T cells in peritoneal cell suspensions of S. enteritidis 11RX (11RX)-infected mice, with the peak of activity occurring 5 days after infection. This did not correlate with the proliferative activity of these cells, which peaked 10-12 days after infection. Secondary challenge with 11RX or S. typhimurium C5 (C5) induced a rapid increase in the cytotoxic activity of Lyt-2+ peritoneal T cells and was detected even 21 days later. The antigen specificity of some of these cells was confirmed in cytotoxicity assays using P815 tumour cells infected with 11RX organisms as targets. No cytotoxic activity was detected in the spleen cell suspensions of infected (and normal) mice unless the cells were first activated by in vitro culture with concanavalin A (Con A). Both types of activated spleen cells showed LDCC but Salmonella-specific cytotoxic Lyt-2+ T cells were detected only in spleen cell (SC) cultures prepared from mice challenged with a second dose of Salmonella.