FIG. 1.

Monocytes support HIV-1 entry. (a) Elutriated monocytes were cultured in the presence of MCSF, and, at daily intervals, cells were removed and immunophenotyped for the indicated cell surface receptors by flow cytometry. ND, not done. (b) Efficiency of HIV-1 entry in monocytes and macrophages. The extent of virus entry was examined as described elsewhere (1, 18). Briefly, monocytes and macrophages were incubated with 2 nM CCF2/AM for 2 h and then infected with wild-type or VSV-G-pseudotyped HIV-1 virions into which a Vpr-β-lactamase fusion protein had been packaged. Two to 4 h postinfection, cells were examined by fluorescence microscopy using 424/444- and 516/520-nm band-pass filters in order to discriminate infected from uninfected cells. The ability of resting lymphocytes, which are refractory to productive HIV-1 infection, to support HIV-1 entry was compared with that of monocytes and macrophages. The effect of spinoculation (21) and Polybrene (3) on the efficiency of monocyte and lymphocyte infection was also examined.