Expression of TRAIL in uninfected and HHV-7–infected activated primary CD4⁺ T cells.

(A) Virus growth was detected by indirect immunofluorescence assay with the HHV-7–specific 5E mAbs. Representative photographs taken 13 days after infection are shown. (left) HHV-7–specific immunofluorescence. (right) DAPI staining of the nuclei of the same field. Original magnification is × 250. (B) Equivalent amounts of protein lysates obtained from HHV-7–infected and uninfected CD4⁺ T cells were analyzed by Western blot with an anti-TRAIL mAb. Equal loading of protein in each lane was confirmed by staining with the antibody to β-actin. Molecular size markers are indicated on the right in kilodaltons. Relative intensities of the bands were densitometrically quantified and expressed in arbitrary units. (C, D) CD4⁺ T cells were either mock-treated (control) or HHV-7 infected and, at 10 to 12 days after infection, cultured with [³H]TdR-labeled CD4⁺ (C) or CD8⁺ (D) T cells at the E/T ratio of 4:1, either in the absence (nil) or the presence of neutralizing anti-TRAIL (1 μg/mL), anti–TNF-α (1 μg/mL), or anti-CD95 Fab′ (0.1 μg/mL) Ab. These results are representative of 5 independent experiments performed.