FACS analysis of CD4, CCR5, and CXCR4 expression on p PBMCs. PBMCs were either stimulated with PHA or PHA/IL-2 (as per conditions for HIV infection) and tricolor FACS analysis was performed. Scatter plots of PBMCs labeled with anti-CD4 PerCP Cy5.5, anti–CCR5 GAM-FITC (or GAM-APC), and anti–CXCR4-PE were analyzed, and background compensated to isotype controls. (A,B) Percentage of cell populations expressing CD4, CCR5, and CXCR4, present in PHA-activated PBMCs (A) or PHA/IL-2-activated PBMCs (B) plotted as histograms for ease of comparison. (C,D) MFI of surface expressed CD4, CCR5, and CXCR4 was measured and fold difference in expression levels calculated based on control values for PHA-activated PBMCs (C) or PHA/IL-2–activated PBMCs (D). represents healthy PBMC controls designated C-p1, C-p2, or C-p3 (Table 3); ■, p PBMCs designated p1, p2, or p3 (Table 2).