The contribution of T lymphocyte subpopulations to intrapulmonary and systemic resistance against an opportunistic strain of Cryptococcus neoformans was examined. It was found that C. neoformans was destroyed when introduced into the lungs of normal mice, but disseminated to the brains of mice treated with an antibody that depleted them of CD4+ T cells. Depletion of either CD8+ or CD4+ T cells impaired the ability of the host to clear the yeast from the lung. These results, together with the observation that CD8+ T cells accumulate in the lungs of CD4+ T cell-deficient mice, suggest that CD8+ T cells play an important role in resistance to C. neoformans infection acquired via the respiratory tract.
