DEPLETION OF IFN-GAMMA, CD8(-DELTA(+) CELLS IN-VIVO DURING PRIMARY INFECTION WITH AN ENTERIC PARASITE (TRICHOSTRONGYLUS-COLUBRIFORMIS) ENHANCES PROTECTIVE IMMUNITY() OR TCR GAMMA)

In order to examine the role of CD8(+) and WCI+ T cells and of IFN-gam ma in the development of protective immunity against infection with th e enteric nematode parasite Trichostrongylus colubriformis in sheep, m Ab were administered during induction of the immune response to deplet e or neutralize these components. Protection against the primary and c hallenge infections were assessed by faecal egg count and total worm c ount. Prolonged administration of mAb recognizing IFN-gamma and CD8(+) resulted in significantly increased protection during the 6-week prim ary infection. CD8(+) cells were depleted from blood but not intestina l mucosa. After injection of mAb (CC15) recognizing the surface antige n WCI, WCI+ and T cell receptor (Tcr) gamma delta(+) cells were deplet ed from blood but not from enteric mucosa. and protection against chal lenge, although variable, was increased by up to 88%. It appears that CD8(+) and WCI+/gamma delta(+) cells and IFN-gamma all retard the pote ntial development of naturally-acquired immunity against the parasite.