Increased CD8(+)-T-cell expression and a type 2 cytokine pattern during the muscular phase of Trichinella infection in humans.

Cell-mediated immunity during the muscular phase of Trichinella infection in humans was studied. Cell proliferation, the phenotypic changes in the T-cell population, and expression and production of cytokines were examined by using peripheral blood mononuclear cells (PBMC) collected at different times postinfection from 10 individuals who had acquired Trichinella spiralis and five individuals who had acquired Trichinella britovi in two distinct outbreaks. T. spiralis and T. britovi crude worm extracts induced proliferation of PBMC from T. spiralis- and T. britovi-infected donors. Cytokine gene expression showed a predominant type 2 pattern for the entire period of infection studied, although gamma interferon (IFN-gamma) was expressed. Interleukin-2 (IL-2), IL-5, IL-10, and IFN-gamma production was found in PBMC of all donors. There was a good correspondence between the cytokine expression and production patterns. Changes in PBMC composition, with a trend toward an increase in CD8(+) lymphocyte counts, were observed.