Expansion of EBV-specific effector T cells in PTLD. Polyclonal EBNA1-specific T cells and polyclonal BZLF1-specific T cells were generated from 19 healthy control and 14 EBV⁺ PTLD PBMCs using the 14-day peptide pool expansion protocol. On day 14, the cells were restimulated with the appropriate peptide pool and assayed for IFN-γ and CD107a/b production using flow cytometry. Results are as follows: (A) Number of IFN-γ or CD107a/b-producing CD8⁺ T cells expanded from 10⁶ PBMCs. (B) Number of IFN-γ–producing CD4⁺ T cells (represented by the CD8⁻ CD3⁺ population). (C) Comparison of EBNA1 and BZLF1-specific IFN-γ–producing CD8⁺ and CD4⁺ T cells