Amplification of adenovirus-specific T cells in vitro. (A) PBMCs from a haploidentical transplant recipient without adenovirus infection were stimulated in vitro with adenovirus antigens to amplify the frequency of adenovirus-reactive T cells and reanalyzed 9 days later by IFN-γ ELIspot. (B) Amplification of adenovirus-specific T cells from a MUD recipient without infection showing an increase in the adenovirus-specific T-cell precursor frequency using IFN-γ ELIspot.