Endogenous interleukin (IL)-1 alpha and IL-1 beta are crucial for host defense against disseminated candidiasis.

BACKGROUND: Interleukin (IL)-1 alpha and IL-1 beta are protective proinflammatory cytokines involved in host defense against Candida albicans. It is, however, unknown whether they provide protection through similar mechanisms. We investigated the effect of endogenous IL-1 alpha and IL-1 beta on disseminated C. albicans infection.
METHODS: Mice deficient in the genes encoding IL-1 alpha (IL-1 alpha-/-), IL-1 beta (IL-1 beta-/-), or both molecules (IL-1 alpha-/- beta-/-) were used. Survival and C. albicans outgrowth in the kidneys was assessed after intravenous injection of C. albicans.
RESULTS: Both mortality and C. albicans outgrowth in the kidneys were significantly increased in IL-1 alpha-/- and IL-1 beta-/- mice, compared with those in control mice, with the IL-1 alpha-/- beta-/- mice being most susceptible to disseminated candidiasis. The host defense mechanisms triggered by IL-1 alpha and IL-1 beta differed from one another. IL-1 beta-/- mice showed decreased recruitment of granulocytes in response to an intraperitoneal C. albicans challenge, and generation of superoxide production was diminished in IL-1 beta-/- granulocytes. IL-1 alpha-/- mice had a reduced capacity to damage C. albicans pseudohyphae. Protective type 1 responses were deficient in both IL-1 alpha-/- and IL-1 beta-/- mice, as assessed by production of interferon-gamma by splenocytes in response to heat-killed C. albicans.
CONCLUSION: Although IL-1 alpha and IL-1 beta have differential effects on the various arms of host defense, both cytokines are essential for mounting a protective host response against invasive C. albicans infection.