Evaluation of (A and B) apoptosis and surface expression of (C) CD95 and (D) CD95L in untreated and FK-treated JBru.mut.8. (A and B) Apoptosis was quantitatively evaluated by PI staining followed by flow cytometry at different culture times after serum starvation in the (A) absence or (B) presence of anti-CD95 IgM. Data are the mean ± SD of three separate experiments in duplicate. (C and D) Surface expression of CD95 and CD95L was detected by indirect staining in cells cultured for 24 hours in RPMI + 0.1% FCS. Unshadowed histograms represent cells treated with (C) anti-CD95 + GAM-FITC or (D) anti-CD95L + GAR-FITC, and shadowed histograms are negative controls (cells treated with anti-p66 of HCMV + GAM-FITC and cells treated with normal rabbit IgG + GAR-FITC). X-axis, relative (C) CD95 or (D) CD95L expression detected by fluorescence intensity (log scale); y-axis, relative number of cells. A representative of four separate experiments is shown. The MFI of the four experiments (AU) was 233 ± 48 (JBru.mut.8) and 251 ± 62 (JBru.mut.8 + FK) in (C) and 43 ± 9 (JBru.mut.8) and 49 ± 17 (JBru.mut.8 + FK) in (D).