CRYPTOCOCCUS-NEOFORMANS AND CANDIDA-ALBICANS REGULATE CD4 EXPRESSION ON HUMAN MONOCYTES

This study examined the capability of Candida albicans and Cryptococcu s neoformans to modulate CD4 expression on human monocytes, C. albican s and an acapsular strain of C. neoformans induced higher levels of CD 4 expression than encapsulated strains. Purified glucuronoxylomannan d id not regulate CD4 expression on monocytes, but down-regulation of CD 4 expression compared with stimulation by acapsular C. neoformans alon e was observed when glucuronoxylomannan was used in combination with a capsular C. neoformans. The ability of opsonic factors to facilitate f ungal-mediated CD4 overexpression suggests that binding or internaliza tion (or both) of the yeast cells is a critical event. Protein synthes is was required, excluding redistribution of the intracellular pool of CD4 receptors to the cellular surface as the sole possible mechanism. Results demonstrate a new effect of fungi on professional phagocytic cells and raise the possibility that modulation of CD4 could influence gp120-mediated human immunodeficiency virus entry.