Virus-specific T-cell responses and cell persistence in post-infusion samples. (A) ELISpot assay showing preinfusion and maximum CMV-induced IFN-γ production within 100 days after infusion. Statistical significance was evaluated with a 2-tailed Wilcoxon matched-pairs signed-rank test. (B) Tetramer responses for 12 patients with >1% expression, showing elevation and persistence over time. (C) Tetramer responses for patient 8 shown in composite at 4 time points. For each time point, biaxial flow plots, tSNE of major cell populations, and blood viral load (below each tSNE plot) are shown. (D) Microchimerism assessed by ddPCR in 15 patients. Informative insertion-deletion polymorphisms (indels) that distinguished the third-party VST donor from the transplant donor and recipient were identified. Adoptively transferred VST product was detected in the peripheral blood of all patients up to day 120 after infusion, all quantified below 3 copies per 100 ng of DNA. Day 0 results were from samples taken 2 hours after VST administration. Patient 6 withdrew from the study and had no further time points after day 92. tSNE, t-distributed stochastic neighbor embedding.