Cell-surface expression of Fas/Fas L on EBV-infected neutrophils. Immunofluorescence flow cytometry was performed on unstimulated neutrophils (white surface) and on EBV-infected neutrophils (black surface) after 20 hours of culture. Analyses were performed on 10,000 cells per sample and data are representative of four independent expriments. The averages for the controls are: Fas, 84 ± 8; Fas L, 6 ± 3; and for EBV-treated cells: Fas, 93 ± 4; Fas L, 15 ± 5.