Expansion of naive and memory p14 T cells in vitro. Naive p14 T cells (A) and memory p14 T cells (B) were restimulated in vitro for 4 days with irradiated nonpulsed splenocytes (▪), gp33-pulsed splenocytes (▦), or αCD3 (□) in the presence of 1 or 5 μM imatinib or DMSO as a solvent control. ³H-thymidine incorporation was measured during the last 14 hours of culture. Results are given as mean ± SEM of 3 to 4 samples per group. One of 2 representative experiments is shown.