ROLE OF THE CAPSULE IN MICROGLIAL CELL-CRYPTOCOCCUS NEOFORMANS INTERACTION - IMPAIRMENT OF ANTIFUNGAL ACTIVITY BUT NOT OF SECRETORY FUNCTIONS

Using two isogenic strains of Cryptococcus neoformans, we studied the influence of the capsule in C. neoformans microglial-cell interaction. We demonstrate that the acapsular mutant yeasts (CAP67) are more susc eptible to phagocytosis and killing than encapsulated yeasts (B3501) b y the murine microglial cells, BV-2. RT-PCR analysis showed that the p attern of gene transcripts for tumour necrosis factor alpha (TNF-a), i nterleukin (IL)-1 beta, IL-6, IL-12p40 and granulocyte macrophage colo ny stimulating factor re:mains unchanged following BV-2 cell infection with CAP67 or B3501 yeasts. Moreover, no induction of TNF-alpha secre tion occurs in BV-2 cells infected with either B3501 or CAP67 yeasts o r exposed to glucuronoxylomannan (GXM) or galactoxylomannan (GalXM). N evertheless, lipopolysaccharide-induced TNF-alpha secretion is downreg ulated by cell infection with B3501 or CAP67 yeasts or exposure to GXM or GalXM. Overall, by means of a continuous cell line, it appears tha t the C. neoformans capsule is detrimental to microglial cell antifung al activity, while no effect can be attributed to the capsule as trend of cytokine gene expression and TNF-alpha secretion.