Identification of EBV-infected lymphocytes and clonality in the peripheral blood of patients. (A) Multicolor FlowRNA cytometric analysis of PBMCs from patients 1 and 2 revealed EBV infection of CD19⁺ B cells. (B) FlowRNA analysis of PBMC from patients 3, 4, and 5 revealed EBV infection of CD4⁺ T cells from patient 3 and 4, and EBV infection of CD56^high NK cells, CD4⁺ and CD8⁺ T cells. The analysis also revealed downregulation of CD3 expression in the EBER^POS across patients 3 to 5. The percentage of total lymphocyte subsets expressing EBERs is given in the upper righthand quadrant. (C) T cells were stained with a panel of 24 antibodies against the TCR-BV epitopes and analyzed by flow cytometry. The percentage of T cells expressing each TCR-BV are represented by Venn diagrams. For patients 3, 4, and 5, all EBER^NEG T cells exhibited polyclonal TCR-BV populations. However, the EBER^POS CD4⁺ T cells from patients 3 and 4 exhibited a large monoclonal TCR-BV expansion (TCR-BV8 for patient 3 and TCR-BV12 for patient 4). In contrast, EBER^POS CD4⁺ T cells from patient 5 exhibited a polyclonal TCR-BV population, whereas the CD8⁺ T cell exhibited a more focused TCR-BV population (TCR-BV13.2). Key: TCR-BV usage.