Phenotypic characterization of HIV-1_BaL-exposed and CD40L-stimulated DCs. Immature DCs were exposed to 1 × HIV-1_BaL for 72 hours with or without CD40L stimulation during the final 24 hours. The expression of CD80 (A), CD86 (B), CD83 (C), and HLA-DR (D) was measured by flow cytometry. Gates were set on large CD1a⁺ CD3^- cells. The box plots (range and median) represent mean fluorescent intensity (MFI) obtained from 8 individual donors. Significant differences compared with the HIV-1_BaL-unexposed, unstimulated DCs were assessed by an unpaired t test and are indicated by ^** (P < .01) and ^*** (P < .001), respectively. The histograms show the cell surface expression of the maturation markers on DCs from one representative donor; medium (solid line), HIV-1_BaL (thin dotted line), CD40L stimulation (solid bold line), and HIV-1_BaL with CD40L stimulation (dashed bold line).