T-LYMPHOCYTE-DEPENDENT AND T-LYMPHOCYTE-INDEPENDENT INTESTINAL SMOOTH-MUSCLE DYSFUNCTION IN THE T-SPIRALIS INFECTED-MOUSE

We examined the profile of increased intestinal muscle contractility a fter primary infection with Trichinella spiralis in the mouse, correla ting it with parasite expulsion. We also examined the extent to which the changes in muscle contraction were T lymphocyte dependent, by infe cting athymic and SCID mice. Infection was accompanied by increased te nsion development by intestinal muscle. Two components of this respons e were identified, a rapid peak increase in tension generation observe d on day 6 postinfection, and a smaller but sustained increase in tens ion evident thereafter in euthymic BALB/c mice. The peak muscle respon se was significantly delayed in infected athymic and SCID mice, along with a corresponding reduction in the magnitude of the sustained compo nent. These changes were accompanied by reduced parasite expulsion in athymic and SCID mice, compared with euthymic mice. Reconstitution of T cell function in athymic mice restored both the acute and sustained profile of muscle contraction seen in euthymic mice, and this was acco mpanied by faster expulsion of the worms. These results identify T cel l-dependent and -independent components of the muscle response to nema tode infection in the mouse and suggest that the onset of the peak. co ntractile response, as well as the magnitude of the sustained muscle r esponse, contributes to parasite eviction from the gut.