CD19-specific T cells proliferate in response to stimulation by CD19⁺ B-ALL and lymphoma cells.

T cells (1 × 10⁵) from a CD19-specific CD8⁺CTL clone were cocultured with 2 × 10⁶ irradiated PBMCs. Some cultures received 1 × 10⁵ irradiated CD19⁺ or CD19⁻ stimulator cells. The 2 × 10⁶ irradiated PBMCs and irradiated stimulator cells, at a 1:1 ratio with the T cells, were re-added after 7 days. One culture condition was the T-cell clone incubated without PBMCs and stimulator cells. Each culture condition was supplemented with 5 U/mL rhIL-2 every 48 hours. The cells were counted after 14 days and nonviable cells excluded by trypan blue staining. The average cell counts and SDs from 3 repeats are presented. In the insert, 10⁵ T cells from a CD19-specific CD8⁺ CTL clone were cocultured as above. Methyl-[³H]thymidine was added after 96 hours and the incorporated counts were measured 18 hours later. The background incorporation of [³H]thymidine by Daudi cells and a LCL was 827 ± 358 and 909 ± 493, respectively. The average cell counts and SDs from triplicates are presented.