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

Hepatitis C virus (HCV)-specific CD8(+) T cells in peripheral blood mononuc lear cells (PBMCs) from patients infected with HCV were quantitatively anal yzed by flow cytometry using an HLA-B*3501-HCV epitope tetrameric complex. In chronic hepatitis C, tetramer(+)CD8(+) T cells were detected at frequenc ies ranging from 0.05% to 0.12% of total CD8(+) T cells. The number of tetr amer(+)CD8(+) T cells in acute phase PBMCs from patients with acute hepatit is C was about 3 to 5 times higher than in recovery phase PBMCs from the sa me patients and in PBMCs from patients with chronic hepatitis C. Expanding tetramer(+)CD8(+) T cells in PBMCs from patients with acute hepatitis C exp ress a CD28(+)CD45RA(-) memory T-cell. phenotype. In contrast, tetramer(+)C D8(+) T cells in PBMCs from patients with chronic hepatitis C did not predo minantly express this phenotype. These tetramer(+)CD8(+) T cells did not ha ve perforin in their cytoplasma, The present study visually showed that a h igh number of circulating HCV-specific CD8(+) T cells in acute phase PBMCs from patients with acute hepatitis C are mostly memory T cells.