Cryptococcus neoformans and Candida albicans regulate CD4 expression on human monocytes.
This study examined the capability of Candida albicans and Cryptococcus neoformans to modulate CD4 expression on human monocytes. C. albicans and an acapsular strain of C. neoformans induced higher levels of CD4 expression than encapsulated strains. Purified glucuronoxylomannan did not regulate CD4 expression on monocytes, but down-regulation of CD4 expression compared with stimulation by acapsular C. neoformans alone was observed when glucuronoxylomannan was used in combination with acapsular C. neoformans. The ability of opsonic factors to facilitate fungal-mediated CD4 overexpression suggests that binding or internalization (or both) of the yeast cells is a critical event. Protein synthesis 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.
Microbiology Section Department of Experimental Medicine, University of Perugia, Italy.
D
D
Pietrella
C
C
Monari
C
C
Retini
B
B
Palazzetti
T R
TR
Kozel
A
A
Vecchiarelli
D015704:CD4 Antigens / Q000096:biosynthesis*; D002176:Candida albicans / Q000187:drug effects / Q000276:immunology*; D003455:Cryptococcus neoformans / Q000187:drug effects / Q000276:immunology*; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D015699:HIV Envelope Protein gp120 / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D013499:Surface Properties; D015854:Up-Regulation
D015704:CD4 Antigens; D015699:HIV Envelope Protein gp120; D011500:Protein Synthesis Inhibitors; D003609:Dactinomycin; D003513:Cycloheximide