Infestação prévia com Myocoptes musculinus altera a resposta imune induzida por Toxoplasma gondii

Abstract

Toxoplasma gondii is a obligate intraccllular parasite induces a Th1 immune response, in both rcsistant, BALB/c and susceptibie, C57BL/6, lineages of mice. Myocoples musculinus is a acarian induces a Th2 immune response. In the present study, we investigated whether chronic infestation with the M. musculinus influences the immunopathology and development of T. gow/ò'-induced Th1 responses, in BALB/c and C57BL/6 lineages of mice. The animais were infested with M. musculinus and one month later were infected with 10 cysts of the ME -49 strain of T. gondii administrated by intraperitoneal route or inoculated orally with 100 cysts of the parasite and the survival and immune response were monitored. We observed that the acarian infestation accelerated mortality by infection with 10 T. gondii cysts administrated by intraperitoneal route in both susceptibie, C57BL/6, and resistant, BALB/c, lineages of mice to the protozoan. The splenocytes supernatant IFN-y were decreased and IL-4, and IL-5 elevated in coinfected mice from both lineages. These changes were associated with severe pneumonia and wasting condition. ín contrast, when inoculated orally with 100 cysts of the parasit e, the acarian infestation ameliorates the pathological intestinal lesions by T. gondii in C57BL/6 mice and delays the mortality. The results suggest that at one hand the immune response induced by the mange interferes in the type-1 immune response induced by T. gondii and it is detrimental to the host, and in the other hand in some condition this response can conírol the severe intestinal lesions induced by an excessive Th-1 immune response.