Kinetics of T-cell functional recovery after HCT and adoptive T-cell infusion. (A) In vivo peripheral blood T cells regain inducible IFN-γ expression. PBMCs obtained following HCT and adoptive T-cell transfer were examined for intracellular IFN-γ expression by flow cytometry following stimulation by PMA and ionomycin as described in “Patients, materials, and methods.” The mean percent of cytokine-positive cells is shown (CD3⁺ T cells, ○; CD8⁺ T cells, ▴; and CD4⁺ T cells, ▪). Results shown are representative of 2 patients (UPN10 and UPN11) examined. (B) Recovery of T-cell IFN-γ secretion after HCT and T-cell infusion: NHL study patient mononuclear cells before and after HCT were stimulated with the phorbor ester and calcium ionophore as described in “Patients, materials, and methods.” Six healthy donors were also tested with the same stimuli, and the mean ± SEM is indicated. Plotted is the average of triplicate wells in spot-forming units per 1 × 10⁵ CD3⁺ cells. UPN14, ♦; UPN15, ▪; UPN20, ▴; UPN23, □; UPN24, •; UPN25, ⋄; UPN26, ▵; UPN27, ○. Arrow along x-axis denotes day of T-cell infusion. (C) Frequency of CMV-specific CD8⁺ T cells in vivo via major histocompatibility complex (MHC) class I tetramer analysis. Tetramer analysis using the CMV pp65 HLA-A2–positive tetramer was controlled with the tetramer specific for the immunodominant HTLV-1 tax peptide. Time points shown are days from hematopoietic stem cell transplantation, which was 13 days prior to activated T-cell infusion. The percentage of CD8⁺ tetramer–positive T cells is shown above the population gated as positive for an HLA-A2–positive subject (UPN23).