Cytotoxic responses against CLL cells of allogeneic T cells.

After stimulation of allogeneic T cells from healthy donors with CD40-activated CLL cells, cytotoxic immune responses are shown in response to unstimulated (closed circles) and CD40-activated CLL cells (closed diamonds) and K562 cells as controls (open circles). Spontaneous release was determined by incubation of target cells in medium alone and maximum release was determined by resuspending the wells with 2% Triton X-100. Specific lysis was determined for each individual experiment as follows: specific lysis (%) = (experimental⁵¹Cr release − spontaneous ⁵¹Cr release)/maximum ⁵¹Cr release − spontaneous⁵¹Cr)release)] × 100 with an effector-target (E/T) ratio of 1:3, 1:10, and 1:30. Error bars represent SD. Results are representative of 4 of 6 experiments performed.