MUCOSAL AND DISSEMINATED CANDIDIASIS IN GNOTOBIOTIC SCID MICE

The alimentary tracts of germ-free SCID (severe combined immunodeficie nt) mice were susceptible to colonization with Candida albicans, Large viable populations (10(6)-10(8) colony forming units g-1) of C. albic ans, in pure culture, were present in all sections of the intestinal t ract. Candida-colonized SCID mice, sacrificed at various time interval s over a 16 week study, manifested chronic superficial mucosal candidi asis of keratinized epithelial surfaces (tongue and stomach). Despite the continuous presence of large viable populations of C. albicans in their intestinal tract, only superficial mucosal candidiasis and no pr ogressive disseminated candidiasis of endogenous origin was evident in these mice. Treatment with cyclophosphamide (100 mg kg-1, intraperito neally) enhanced the susceptibility of SCID mice to mucosal (tongue an d stomach) candidiasis. Gnotobiotic (C. albicans-colonized) SCID mice were also found to be as resistant as immunocompetent BALB/c mice to a cute (intravenous challenge) renal candidiasis. Colonization of the al imentary tract with a bacterial flora appeared to enhance the resistan ce of SCID mice to disseminated candidiasis. This study demonstrates t hat innate immune mechanisms (phagocytic and/or NK cells), in the abse nce of functional T- and B-cells, play an important role in the resist ance of SCID mice to mucosal and disseminated candidiasis of endogenou s (intestinal tract) or acute (intravenous challenge) origin.