DEPRESSED T-CELL PROLIFERATION-ASSOCIATED WITH SUSCEPTIBILITY TO EXPERIMENTAL TAENIA-CRASSICEPS INFECTION

Peritoneal infection with Taenia crassiceps cysticerci of naturally re sistant (C57BL/10J and C57BL/6J) and susceptible (BALB/cAnN) mice indu ces a cellular immune depression, T-cell proliferation in response to concanavalin A (ConA) or anti-CD3 was significantly depressed in infec ted mice of all strains tested, However, in resistant mice, the dimini shed response to ConA was transient and animals recovered normal respo nsiveness at day 40, whereas susceptible mice remained suppressed thro ughout the 40 days of the experiment. In contrast, the proliferative r esponse to anti-CD3 was lower in infected mice than in noninfected con trols regardless of differences in natural susceptibility of the strai ns. Intraperitoneal injection of mice with a parasite extract also ind uced a depression of the response to ConA, although not as strong as t hat produced by the parasite itself, This depression is not due to dir ect effects by parasite antigens over host lymphocytes, as proliferati on is not affected by the presence of cysticercal antigens added in vi tro, Diminished interleukin-2 production during the parasitosis accoun ts at least in part for the diminished responses to ConA. A primary in fection favors parasite establishment after a second challenge, pointi ng to the relevance of the immunodepression in generating a host envir onment favorable to the parasite.