Antigen-presenting characteristics of peritoneal cells of Salmonella enteritidis 11RX-infected mice.

Investigation of the possibility that infection with intracellular bacterial parasites such as Salmonellae may modulate the function of antigen-presenting cells (APC) revealed no major change in APC function of peritoneal cells (PC) harvested from the peritoneal cavity of mice 1-3 days after intraperitoneal immunization with S. enteritidis 11RX. Analysis of the phenotype of the Salmonella-primed T cells which responded when cultured with PC from either normal or infected mice and Salmonella-antigen showed that only L3T4+ T cells proliferated. This was also true when PC from normal and infected mice were compared for their ability to induce allogeneic responses; both L3T4+ and Lyt-2.2+ T cells were induced to proliferate, with the majority belonging to the class I restricted, Lyt-2.2+ phenotype. Significant levels of alloantigen-specific Lyt-2.2+ cytotoxic T-cell activity were also induced in both types of cultures. However, a minor population of adherent cells which inhibited Salmonella antigen-specific T-cell proliferation in vitro was detected in peritoneal cell suspensions harvested 3 days after intraperitoneal immunization with S. enteritidis 11RX. Further characterization of these peritoneal cells revealed that they also inhibited the induction of in vitro T-cell responses to alloantigens. It is likely that the cells mediating these inhibitory effects belonged to a macrophage-like subset.