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.