THE ROLE OF CD4(-CELLS IN PROTECTIVE IMMUNITY TO THE MURINE NEMATODE PARASITE TRICHURIS-MURIS() AND CD8(+) T)

The role of CD4(+) and CD8(+) T cells in protective immunity to Trichu ris muris was studied in CD4(+) or CD8(+) or bath CD4(+) and CD8(+) T cell-depleted BALB/c mice. To assess in vivo depletion of T-cell subse ts, CD4(+) and CD8(+) T cells in the Peyer's patches, the mesenteric l ymph nodes (MLN), and the spleens of mice treated with T cell-specific monoclonal antibodies (MoAbs) were analysed by FACS. CD4(+) T cells w ere selectively depleted in mice injected with anti-CD4 MoAb i.p. and injection of anti-CD8 MoAb resulted in selective depletion of CD8(+) T cells. The expulsion of T. muris was inhibited in CD4(+) T cell-deple ted mice and numerous worms were detected in the large intestine on da ys 14 and 21 after infection, although no suppression of protective im munity to T. muris was observed in CD8(+) T cell-depleted mice. Moreov er, there was no difference in suppression of protective immunity to T . muris between CD4(+) T cell-depleted and both CD4(+) and CD8(+) T ce ll-depleted mice. These results indicate that CD4(+) T cells play a ce ntral role in protective immunity to T. muris infection.