Immunosuppression in Trypanosoma brucei infections in rats and mice

TLDR: In rats in which N. brasiliensis infection was superimposed on a previously existing T. brucei infection, the normal process of immune expulsion of adult worms did not occur, the production of circulating protective antibody and of reaginic antibody was grossly impaired and there was no increase in the numbers of mast cells in the intestinal villi.

Abstract: In rats in which N. brasiliensis infection was superimposed on a previously existing T. brucei infection of 3 weeks' duration, the normal process of immune expulsion of adult worms did not occur, the production of circulating protective antibody (IgG) and of reaginic antibody (IgE) was grossly impaired and there was no increase in the numbers of mast cells in the intestinal villi. In contrast to this failure of humoral and immediate-type responses, cell-mediated immunity, as measured by oxazolone sensitization of mice with a T. brucei infection, still occurred to a significant extent although not so markedly as in uninfected mice. These results, which provide further evidence that infection with T. brucei may induce a significant degree of immunosuppression of the host, are discussed with particular regard to the aetiology of the phenomenon.