Figure 8. Transplant recipients exhibit a T_EM phenotype and react spontaneously to tumor ex vivo.

(A) PB samples at 6 months post-transplantation were obtained and stained with antibodies against CD4, Tyrp1 Ultimer, CD44, CD45RB, and CD62L. LV-TCR transplant CD4⁺Ultimer⁺ cells exhibited a T_EM phenotype (CD45RB^loCD62L^loCD44^hi), while the polyclonal CD4⁺Ultimer^– and CD4⁺ control population exhibited a more generalized effector profile (CD45RB^hiCD62L^intCD44^hi), in contrast with naive CD4⁺Ultimer⁺ cells (CD45RB^hiCD62L^hiCD44^lo) from endogenous nontransplanted TCR Tg. (B) Summary of activation status of all CD4⁺ subpopulations. (C) Gene-modified T cells exhibited a Th₁-polarized cytokine profile in response to specific peptide and tumor. Splenocytes from 6-month-old LV-TCR and LV-GFP transplants were stimulated ex vivo for 24 hours with peptide (Tyrp1_277–297 or HA_306–318) or tumor (MC38-DR4 or B16-DR4). Cytokine release (IFN-γ) was measured by ELISA. Data (mean ± SEM; n = 5 per group) and flow cytometry are representative of 3 independent experiments.