Figure 8. Human pSTAT3–inhibited iTregs maintain antileukemia immunity by donor T cells.

Graph depicts mean lysis ± SEM by U937-specific, human T cells generated in vivo using NSG mice transplanted with human PBMCs, pSTAT3-inhibited (S3i) or control iTregs, and then vaccinated with irradiated U937cells (2 × 10⁶, ATCC) on days 0 and +7. Human T cells from nonvaccinated mice containing PBMCs alone group served as a negative control. On day +12, the mice were euthanized, and human T cells were harvested and purified from the spleen using magnetic bead separation. Tregs were specifically not removed from the harvested T cells. The purified T cells were cultured with fresh U937 targets at varying ratios. U937 lysis was measured using a colorimetric assay after 4 hours of culture. Results shown are from 1 of 2 independent experiments, using 4 mice per group. ANOVA. ****P < 0.0001. pSTAT3, STAT3 phosphorylation; iTregs, induced Tregs.