Expansion of adenovirus-specific T cells in peripheral blood of recipients of VSTs by ELISpot. (A) Quantitation of the number of adenoviral T cells before VSTs compared with the peak number in the first 4 weeks after infusion presented as SFCs. Graph shows data from patients with clinical response and an increase in T-cell number after infusion. For patients with multiple infusions, data reflect T-cell increase after the first infusion that resulted in a response. (B-C) Inverse relationship between frequency of circulating VSTs and adenoviral burden. (B) Representative examples of 3 VST recipients who had CRs after infusion with a corresponding increase in T-cell number by ELISpot. (C) ELISpot in 1 patient with no clinical response; note small scale of the y-axis demonstrating minimal T-cell numbers. Open symbols denote number of SFCs per 400 000 PBMCs. Solid symbols denote adenoviral burden in peripheral blood. UPN, unique patient number.