The role of CD8+ T cells in the pathogenesis of Pneumocystis carinii pneumonia in mice depleted of CD4+ T cells.

OBJECTIVE

To define the cell populations contributing to inflammation-associated respiratory impairment in Pneumocystis carinii pneumonia (PCP).

METHODS

The host inflammation response was observed in CD4+ T cell-depleted mice and in CD4+ and CD8+ T cell-depleted mice infected with P. carinii via intratracheal inoculation.

RESULTS

Mice depleted of both CD4+ and CD8+ T cells developed infection with neither increased respiratory rate nor lung injury. In contrast, mice depleted of CD4+ T cells alone exhibited severe pulmonary inflammation, and increased respiratory rates. Respiratory compromise was associated with the presence of activated CD8+ cells and neutrophils in the BALF.

CONCLUSION

The host's inflammatory cell response to P. carinii directly impairs pulmonary function and contributes to the pathogenesis of PCP, CD8+ T cells appear to play a major role.