IN-VIVO DEPLETION OF T-CELLS AND CYTOKINES DURING PRIMARY EXPOSURE OFSHEEP TO PARASITES

This study examined the role of CD8+ and WC1 + T-cells and of interfer on (IFN)-gamma in the development of protective immunity against infec tion with the enteric nematode parasite Trichostrongylus calubriformis in sheep, Monoclonal antibodies (mAb) were administered during induct ion of the immune response to deplete or neutralise these components. Protection against the primary and challenge infections was assessed b y faecal egg count and total worm count. Prolonged administration of m Ab recognising IFN-gamma and CD8 resulted in significantly increased p rotection during the 6 week primary infection and following challenge. CD8+ cells were depleted from blood but not from intestinal mucosa. A fter injection of mAb (CC15) recognising the surface antigen WC1, WC1 + and Tcr gamma delta + cells were depleted from blood but not markedl y from enteric mucosa, and protection against challenge, although vari able, was increased by up to 88%. It appears that CD8+ and WC1 +/gamma delta+ cells and IFN-gamma all retard the potential development of na turally acquired immunity against the parasite.