Cell surface expression of human FcγRI, II, and III; HLA class I and II; CD4; and IL-2R molecules in an HMØ population transfected with HIV-1 Nef or HIV-1 fen plasmid. After AD, dl312-mediated transfection of nef cDNA, HMØs were cultured and analyzed for expression of cell surface molecules. Cells in separate tubes were suspended in modified Hank's buffer. FITC-labeled specific monoclonal antibody was added; after incubation, cells were washed and analyzed by fluorescence histograms. FITC-labeled similar isotype antibody was added as control in each case. Downregulation of FcγRI, II, and III and CD4 and upregulation of HLA class I molecules and no change in IL-2R and HLA class II were observed in a Nef-expressing population of HMØs.