The role of CD4+ and CD8+ T cells in protective immunity to the murine nematode parasite Trichuris muris

The role ofCD4⁺ and CD8⁺ T cells in protective immunity to Trichuris muris was studied in CD4⁺ or CD8⁺ or both CD4⁺ and CD8⁺ T cell-depleted BALB/c mice. To assess in vivo depletion of T-cell subsets, CD4⁺ and CD8⁺ T cells in the Peyer's patches, the mesenteric lymph nodes (MLN), and the spleens of mice treated with T cell-specific monoclonal antibodies (MoAbs) were analysed by FACS. CD4⁺ T cells were selectively depleted in mice injected with anti-CD4 MoAb i.p. and injection of anti-CD8 MoAb resulted in selective depletion ofCD8⁺ T cells. The expulsion ofl. muris was inhibited in CD4⁺ T cell-depleted mice and numerous worms were detected in the large intestine on days 14 and 21 after infection, although no suppression of protective immunity to T. muris was observed in CD8⁺ T cell-depleted mice. Moreover, there was no difference in suppression of protective immunity to T. muris between CD4⁺ T cell-depleted and both CD4⁺ and CD8⁺ T cell-depleted mice. These results indicate that CD4⁺ T cells play a central role in protective immunity to T. muris infection.