Determination of HCV-Specific Bulk CD8+ Activity in Liver

The host immune response to hepatitis C virus (HCV) infection comprises both humoral and cellular components, which accompany all viral infections. The cellular immune response involves both nonspecific and antigen-specific phases, with recovery thought to be largely dependent on classical CD4⁺ and CD8⁺ cytotoxic T-lymphocytes (CTLs). Intracellular and extracellular antigens present quite different challenges to the immune system, both in terms of recognition and appropriate response. In general, T-cells do not recognize native antigen; rather, they recognize short antigenic peptides that have been processed and presented on the cell surface. For an appropriate response, it is necessary that the T-cell receptor recognize a ligand composed of processed viral immunogenic peptide bound to a major histocompatibility complex (MHC) molecule on the surface of an antigen-presenting cell or target cell. Processed peptides are generally presented to CD8⁺ cells by MHC class I molecules, which are expressed on virtually all cells.