Changes in the composition of circulating CD8(+) T cell subsets during acute Epstein-Barr and human immunodeficiency virus infections in humans

In response to viral infection, unprimed naive CD8(+), major histocompatibi lity complex class I-restricted, virus-specific T cells clonally expand and differentiate into memory- and effector-type cells. Changes in CD8(+) subs et distribution were studied in 17 subjects with acute human immunodeficien cy virus type 1 infection and in 14 subjects with acute Epstein-Barr virus (EBV) infection, with combined CD45RO, CD27, and CD28 monoclonal antibodies . A vast expansion of memory-type CD45RO(+)CD27(+)CD8(+) T cells, with high expression of the cell-cycle marker Ki-67, was observed in both infections . Strikingly, CD45RO(+)CD27(+)CD28(-) cells increased >10-fold in acute vir al infection and had high Ki-67 expression. In acute EBV infection, a subst antial portion of the expanded T cells were EBV-peptide specific. These cel ls resided mainly in the CD45RO(+)CD27(+) subpopulation, with most in the C D27(+)CD28(-) subpopulation. Content of perforin expression, as a measure o f cytotoxic capacity, was relatively low in the CD27(+)CD28(+) T cells and highest in the CD27(-)CD28(-) subpopulation.