It is believed that the hepatitis C virus (HCV)-specific CD8(+) cytotoxic T lymphocytes (CTLs) play a role in the development of liver cell injury and in the clearance of the virus. To develop a direct binding assay for HCV-specific CTLs, we generated two peptide-MHC tetramers by using the recombinant HLA A2.1 molecule and A2-restricted T cell epitopes of the HCV NS3 protein. With these reagents we are able to detect specific CD8(+) cells in the blood of 15 of 20 HLA-A2(+), HCV-infected patients, at a frequency ranging from 0.01% to 1.2% of peripheral CD8(+) T cells. Phenotypic analysis of these specific cells indicated that there is a significant variation in the expression of the CD45 isoforms and CD27 in different patients. A 6-hour incubation of one patient's blood with NS3 peptides resulted in the activation of the epitope-specific CD8(+) cells, as indicated by their expression of CD69 and IFN-gamma. We also detected NS3-specific CD8(+) T cells in the intrahepatic lymphocyte population isolated from liver biopsies of two HCV-infected patients. The frequency of these specific CD8(+) cells in the liver was 1-2%, at least 30-fold higher than in the peripheral blood. All of the intrahepatic NS3-specific CD8(+) T cells were CD69(+), suggesting that they were activated CTLs. Direct quantitation and characterization of HCV-specific CTLs should extend our understanding of the immunopathogenesis and the mechanism of clearance or persistence of HCV.
View details for Web of Science ID 000080246500068
View details for PubMedID 10318946