Fc receptor expression on human immune effector cells. (A) Representative flow cytometric histogram showing the surface expression of selected Fc receptors (FcR) on purified human monocytes used for ADCP with gp140-coupled beads (left). FI, fluorescence intensity. Gray histograms correspond to unstained cell controls. Dot plot shows the surface expression of selected FcR on human monocytes purified from four donors (right). Percentage of CD16^high cells (left y axis) and ΔMFI for all FcR are shown. (B) Representative flow cytometric histogram showing the binding of recombinant Fc proteins and IgA1 antibodies to purified human monocytes used for ADCP with gp140-coupled beads (left). Dot plot shows the binding of Fc proteins and IgA1 antibodies to human monocytes purified from four donors (right). m, monomeric; d, dimeric. (C) Representative flow cytometric histogram showing the binding of 10-1074 IgG antibodies to YU2 gp140-F-coupled FITC beads. mGO53 antibody is the negative isotypic control. (D) Same as in A but for purified human monocytes and neutrophils used as effectors in co-culture with HIV-1–infected CEM-NKR-CCR5 cells.