Human retinal microglia express candidate receptors for HIV-1 infection.

BACKGROUND/AIMS Microglia are the primary antigen presenting cells in the central nervous system and the retina, and can harbour viral antigens that may damage neural tissue via the release of neurotoxins. All cells bearing CD4 molecules and co-receptors (members of the chemokine receptor and Fcgamma receptor families) are potential targets for the human immunodeficiency virus (HIV). In this study, retinal microglia (in vitro and in situ) were investigated for the expression of candidate HIV-1 binding receptors. METHODS Cultured human retinal microglia and frozen sections of human retinas were used. Immunohistochemistry was used to investigate expression of cell surface receptors necessary for HIV-1 infection: CD4, CC chemokine receptor 5 (CCR5), and Fcgamma receptors. RESULTS Human retinal microglia expressed detectable levels of CD4, CD16, CD64, and CCR5 in vitro and Fcgamma receptor I (CD64) in situ. CONCLUSIONS Human retinal microglia express several candidate receptors required for viral binding and as such may be a potential reservoir for HIV-1 infection.