Expression of cell-free soluble and membrane-associated Fas-L by lymphocytes from HIV-1–infected persons. (A and B) Expression of Fas-L on normal (HIV⁻) and HIV-1–infected lymphocytes. Lymphocytes from HIV-1–infected patients (N = 10) and normal controls (N = 10) were dually stained with PE-conjugated CD4 or CD8 MoAb and FITC-conjugated anti–Fas-L. Columns at the left represent the numbers of CD4 or CD8 cells that reacted with Fas-L (B). An example scattergram (A) showing binding of CD4 PE on the Y axis and anti–Fas-L (FITC) on the X axis for both an HIV-1–infected patient and a normal control are represented. (C) Western blot of cell-free suspension from cultures from normal donors and lymphocytes from HIV-1–infected patients. PBMCs from normal controls (N = 20) and HIV-1–infected patients (N = 20) were cultured as previously described for 72 hours. Cell-free supernatants were prepared as described in Materials and Methods, and samples were analyzed by Western blotting using MoAb to Fas-L.