Schistosomal egg antigen-responsive CD8 T-cell population in Schistosoma mansoni-infected BALB/c mice

We demonstrated here that schistosomal egg antigen (SEA) is able to stimula te an antigen-specific, cytotoxic CD8(+) T-cell response in mice. Indeed, a single i.p. immunization with SEA resulted in the in vivo induction of sig nificant cytotoxic T lymphocyte (CTL) activity in the spleen within 20 days . Effector cells were classic class I major histocompatibility complex (MHC )-restricted CD8(+) lymphocytes producing interferon-gamma (IFN-gamma) and interleukin-2 (IL-2), suggesting a type 1 response to SEA. We therefore inv estigated the relevance of these observations in the context of the Schisto soma mansoni parasite infection. CTL activity against SEA-pulsed target cel ls was evidenced throughout the infection after in vitro stimulation of rec overed splenic cells with SEA demonstrating that SEA-specific CD8(+) T cell s with cytotoxic potentialities are present during infection. This activity was strongly increased after immunization of mice with SEA like the produc tion of IFN-gamma in the sera. A marked reduction in the number of granulom as and of fibrosis with the presence of cells producing IFN-gamma in the li ver was also observed leading to the survival of SEA-immunized mice.