Characterization and in vivo fate of donor-derived mLSTs. (A-C) Characterization of donor-derived mLSTs. (A) Phenotype and memory/activation profile. (B) Specificity of mLSTs as measured by IFNγ ELIspot for 15 products generated using all 3 antigens as a stimulus. Data are shown as mean SFCs ± SEM/2 × 105 and each color represents an individual antigenic specificity. (C) Lack of in vitro mLST cytolytic activity against normal recipient cells at effector/target ratios from 40:1 to 5:1. (D) In vivo behavior of mLSTs in patients who remain in remission (n = 6). Expansion of T cells specific for targeted TAAs (left) and other nontargeted TAAs (right) in patients who responded to therapy. Results are reported as mean SFCs ± SEM/2 × 105 at each specified time point. (E) In vivo behavior of mLSTs in patients who relapsed. Lack of T-cell expansion against either targeted (left) or nontargeted TAAs (right) immediately after infusion in patients 3 and 12 who eventually relapsed. Results are reported as SFC/2 × 105 at each specified time point. Arrows indicate the time of relapse.