Visual demonstration of hepatitis C virus‐specific memory CD8+ T‐cell expansion in patients with acute hepatitis C

Abstract Hepatitis C virus (HCV)-specific CD8 + T cells in peripheral blood mononuclear cells (PBMCs) from patients infected with HCV were quantitatively analyzed by flow cytometry using an HLA-B*3501-HCV epitope tetrameric complex. In chronic hepatitis C, tetramer + CD8 + T cells were detected at frequencies ranging from 0.05% to 0.12% of total CD8 + T cells. The number of tetramer + CD8 + T cells in acute phase PBMCs from patients with acute hepatitis C was about 3 to 5 times higher than in recovery phase PBMCs from the same patients and in PBMCs from patients with chronic hepatitis C. Expanding tetramer + CD8 + T cells in PBMCs from patients with acute hepatitis C express a CD28 + CD45RA − memory T-cell phenotype. In contrast, tetramer + CD8 + T cells in PBMCs from patients with chronic hepatitis C did not predominantly express this phenotype. These tetramer + CD8 + T cells did not have perforin in their cytoplasma. The present study visually showed that a high number of circulating HCV-specific CD8 + T cells in acute phase PBMCs from patients with acute hepatitis C are mostly memory T cells. (H EPATOLOGY 2001;33:287-294.)