Growth inhibition of Candida albicans hyphae by CD8+ lymphocytes

We have shown previously that IL-2-activated splenocytes can inhibit the growth of Candida albicans hyphae in vitro. Herein we demonstrate that plastic nonadherent lymphocytes that are CD8+ mediate the antifungal activity. Enrichment for CD8+ cells markedly enhanced the antifungal activity of the IL-2-activated lymphocyte population for C. albicans and the cytotoxic activity of the lymphocytes for an NK-resistant cell line. Depletion of CD8+ cells reduced the lymphocyte population's antifungal activity and cytotoxic activity for the NK-resistant cell line. Enrichment for NK1.1+ cells markedly reduced the antifungal activity of the lymphocyte population for C. albicans and increased the cytotoxic activity of the lymphocytes for an NK-sensitive cell line. Depletion of NK1.1+ cells increased the lymphocyte population's antifungal activity and cytotoxic activity for the NK-resistant cell line. Generation of the antifungal lymphocytes in culture required IL-2 and was not replaced with IFN-gamma. These data show that IL-2-activated CD8+ T lymphocytes exert the greatest amount of antifungal effect against the hyphal form of C. albicans, whereas IL-2- or IFN-gamma-activated NK cells have little or no effect against the hyphae.