Defective grzB/CTL-mediated cytotoxicity in HL cells. (A) PBMCs from healthy volunteer donors were activated at a density of 5 × 10⁶ cells/mL by ConA (2 μg/mL) in complete RPMI medium for 5 days. Redirected CTL activity was assayed by coincubating for 4 hours ⁵¹Cr-labeled target cells at graded effector-target ratios with activated PBMCs in the presence of ConA (5 μg/mL). Thereafter, the activity of ⁵¹Cr was measured in the cell-free supernatants using a gamma counter. Jurkat T-cell as well as L1309 B-cell lines were used as positive controls for CTL-mediated target cells lysis. (B) Control L1309 B cells and Jurkat T cells (□) or L428 and L540 HL cells () (all 10⁶) were treated with adenovirus at an moi of 100 with or without 600 ng/mL isolated human grzB and incubated for 4 hours at 37°C. Data are mean ± SD values from 3 different individual experiments performed in triplicate.