Expansion of CMV-specific CD4 and CD8 T cells after CD8-depleted DLIs. Before and after CD8-depleted DLIs, the frequencies of CMVpp65-specific T cells were determined within purified CD4 and CD8 blood lymphocytes of CMV^pos patients 8, 4, 17, and 12 by IFN-γ ELISPOT assays. Numbers indicate CMVpp65-specific CD4 (-○-) and CD8 (-•-) T cells × 10⁶/L. All donors were unrelated volunteers with full HLA match, and were either seropositive (patient 8) or seronegative (patients 4, 17, 12) for CMV. Donor PBMCs were also screened for CMVpp65-specific CD4 (□) and CD8 (▪) T cells in IFN-γ ELISPOT assays. Longitudinal bars (⊡) indicate duration of CMVpp65 antigenemia. R, recipient; D, donor.