Quantification of EBV-specific T cells in 2 HLA-B8⁺ patients with HLA tetramers.

Serial PBMC samples from 2 HLA-B8⁺ patients were analyzed by flow cytometry with APC-conjugated MHC/peptide tetramers. Representative results obtained at 3 time points with the HLA-B8 tetramer containing the RAKFKQLL peptide (HLA-B8/RAK) from the EBV immediate early gene BZLF-1 are shown in panel A. CD3⁺ events occurring in a lymphocyte gate are shown in blue. The percentage of CD8⁺ HLA-B8/RAK⁺ events is indicated in the upper right quadrant of each plot. (B) The serial analysis of RAK⁺ CD8⁺ cells in each patient, with RAK-specific CD8⁺ T cells represented as the percentage of CD8⁺ T cells (left) and as the absolute number (per microliter) in peripheral blood, calculated from the absolute CD8⁺ T-cell number determined by flow cytometry of fresh peripheral blood when available (right). Treatment day 0 is defined as the day when reduction of immunosuppression was initiated. Analysis with the additional tetramer reagent, HLA-B8/FLR (FLRGRAYGL; from the EBV latent gene EBNA-3A), is also shown.