Frequency of CMV-specific T cells in vivo. (A) Frequency of CMVSTs in the peripheral blood before (pre) infusion and after (post) infusion, as measured by using the IFN-γ ELISPOT assay after overnight stimulation with IE1 and pp65 viral PepMixes. Results are expressed as SFCs per 5 × 10⁵ input cells (mean ± SEM, n = 10). (B) Persistence of infused CMVSTs in individual patients. Frequency of T cells in peripheral blood as measured by using the IFN-γ ELISPOT assay after stimulation with epitope-specific CMV peptides with restriction to HLA antigens exclusive to the CMVST line or shared between the recipient and the CMVST line.