UVB-INDUCED DECREASED RESISTANCE TO TRICHINELLA-SPIRALIS IN THE RAT IS RELATED TO IMPAIRED CELLULAR-IMMUNITY

Our laboratory has demonstrated in preliminary experiments that UVB ex posure using the Kromayer lamp can induce increased numbers of Trichin ella spiralis larvae in carcasses of infected Wistar rats, without aff ecting specific antibody titers to this parasite. In this study, orall y T, spiralis-infected Wistar rats were exposed to suberythemal doses of UVB radiation using FS40 tamps during different time periods before or after infection, A significant increase in the number of T, spiral is larvae was found in the carcasses of rats that were UVB irradiated daily for 7 consecutive days in the second week after infection. Addit ionally, increased numbers of larvae were also detected histologically in the tongue of rats that were exposed the first and the second week after infection, Lymphocyte stimulation assays using mesenteral lymph node cells indicated that UVB exposure also impaired the specific lym phocyte response to T. spiralis. Moreover, DTH responses to T. spirali s were severely impaired in rats that were UVB irradiated daily for 7 consecutive days in the second week after infection, Thus, these data combined with the data of the Kromayer study indicate that exposure of rats to FS40 irradiation following oral infection with T, spiralis le ads to increased numbers of larvae in systemic sites and impaired T-ce ll immunity to the parasite.