EBER^POS and EBER^NEG cells exhibit differences in their phenotype and function. (A) EBER^POS and EBER^NEG CD4 T cells from patients 3 and 4 were stained for CCR7 and CD45RA, (B) Ki-67 and CD38, (C) Foxp3 and CD25, and (D) TNF-α and IFN-γ. Age-matched healthy donors were also analyzed; 2 representative donors are shown. The analysis revealed the EBER^POS cell expressed markers consistent with memory T cells: they were activated and proliferative, they were not Tregs, and they expressed significant amounts of proinflammatory cytokines. In contrast, the EBER^NEG CD4⁺ T cells closely resembled the phenotype and function of the healthy donor CD4⁺ T cells.