IFN-α induces expression of TRAIL in primary PEL cells.

(A) AZT and IFN-α synergize to induce apoptosis in primary PEL cells (BCLM). Cells were treated for 36 hours with medium, AZT 10 μg/mL, IFN-α 1000 U/mL, or AZT 10 μg/mL plus IFN-α 1000 U/mL. Cells were analyzed for apoptosis by PI/annexin-V staining and FACS analysis. Top and bottom right quadrants of each box are the apoptotic populations. (B) IFN-α induces TRAIL surface expression in primary PEL cells. BCBL-1 and BCLM cells were treated for 24 hours with medium or IFN-α 1000 U/mL and assayed for TRAIL expression by FACS analysis. (C) TRAIL mRNA is induced by IFN-α but not by AZT in primary PEL cells. BCLM cells were treated with medium; IFN-α for 8, 16, 24, and 32 hours; or AZT 10 μg/mL for 36 hours and examined for TRAIL mRNA expression by RNAse protection assay. Reduced glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression was used as an internal control. (D) Primary PEL cells express TRAIL receptors. BCLM surface expression of DR-5 (dotted line) and DR-4 (solid line) was determined by FACS analysis. Shaded area is mouse isotype control (IgG1).