DETECTION OF SALMONELLA-SPECIFIC L3T4(-2(+) T-CELLS WHICH CAN PROLIFERATE IN-VITRO AND MEDIATE DELAYED-TYPE HYPERSENSITIVITY REACTIVITY() AND LYT)

This study was based on an initial observation that, although culture of T cells from salmonella-infected mice with concanavalin A induced b oth L3T4(+) T cells and Lyt-2(+) T cells to proliferate, there was a r elative increase in the responsiveness of the Lyt-2(+) T cells in susp ensions harvested from mice with secondary infection. Accordingly, pri med T cells, obtained from the peritoneal cavities and spleens of mice that had received one or two intraperitoneal doses of Salmonella were examined for the presence of antigen-specific, class I major histocom patibility complex (MHC)-restricted Lyt-2(+) T cells. After primary in fection with avirulent Salmonella enteritidis 11RX (11RX) only L3T4(+) T cells could be induced to proliferate in response to formalin-kille d 11RX organisms, and a second dose of live 11RX did not change the ph enotype of the responding T-cell population. In contrast, secondary ch allenge with S. typhimurium C5 (C5) generated cell populations where b oth L3T4(+) and Lyt-2(+) T cells proliferated when cultured with forma lin-killed 11RX. Transfer of delayed-type hypersensitivity (DTH) using mixtures of primed T cells and either killed or live Salmonella organ isms demonstrated that DTH was mediated by L3T4(+) T cells, and second ary infection with either the 11RX or C5 strain did not change this re sult. However, antigen-specific Lyt-2(+) T cells which mediated DTH re activity were detected using a Salmonella-infected cell line which exp ressed MHC-coded class I but not class II products. These Lyt-2(+) T c ells were present in the spleen and peritoneal cavity after secondary infection and in the peritoneal cavity late after a primary infection with 11RX.