EBV virus loads and EBV-specific CD8⁺T-cell responses in PBMCs from 5 XLP patients. (A) EBV genome load in 10⁶ PBMCs was estimated by quantitative polymerase chain reaction analysis. The normal donor value reported represents the median and the 25-75 percentile range of 600 healthy donors, while the dashed line indicates the upper level of the normal range observed in healthy donors. nt indicates not tested. (B) IFN-γ ELISpot analysis of EBV-specific PBMCs taken from 5 XLP donors. PBMCs were stimulated with known immunodominant EBV epitopes appropriate for their HLA type or the peptide solvent dimethyl sulfoxide (DMSO)as a control. Normal ranges of responses from healthy donors are shown.