Increased resistance to systemic candidiasis in athymic or interleukin-10-depleted mice

Candida albicans produces a virulence-associated immunomodulatory protein ( p43), which activates lymphocytes polyclonally, suppresses specific antibod y responses to Candida antigens, and potentiates systemic growth of C. albi cans. In this study, athymic, unlike euthymic, C57BL/6 mice were resistant to systemic candidiasis and produced lower serum levels of interleukin (IL) -4 and IL-10. Pretreatment with p43 stimulated the production of both cytok ines. Depletion of IL-10, but not of IL-4, in euthymic animals reestablishe d resistance and abrogated p43-dependent suppression of the specific antibo dy response and facilitated C. albicans growth. In agreement with these res ults, both immunosuppression and p43-mediated facilitation of the fungus gr owth were abolished in IL-10 knockout mice. These observations demonstrate the relevance of IL-10 in facilitating systemic candidiasis and suggest a c ritical role for the immunosuppressive virulence factor p43 in the process.