[Role of CD4-CD8- T cells in the murine hepatitis virus type 3 induced chronic viral hepatitis].

Objective To investigate role of CD4-CD8-T cells in murine hepatitis virus type 3 (MHV-3) induced chronic viral hepatitis in C3H/Hej mice and to identify their surface markers. Methods Thirty C3H/Hej mice received 10 Pfu MHV-3 intraperitoneally, the CD4-CD8-T cells were isolated using magnetic bead sorting on 0, 4, 15, 30, 40 days post MHV-3 infection. The cytotoxie effects of CD4-CD8-T cells on normal and infected hepatocytes, CD8+T cells and unrelated-virus (murine cytomegalovirus, MCMV) infected CD8+ T cells were examined by non-radioactive cytotoxicity assay. The surface markers of CD4- CD8- T cells were determined by flow cytometry. Results MHV-3 infected CD4-CD8-T cells showed significant cytotoxic effect on CD8+ T cells, but not on infected hepatocytes or MCMV infected CD8+ T cells. The analysis of cell surface markers demonstrated that the CD4-CD8-T cells are a completely new T cell subset. Conclusions CD4-CD8-T cells have significant cytotoxic effect on virus specific CD8+T cells in MHV-3 infected C3H/Hej mice, which suggests that CD4-CD8-T cells have immune modulatory functions in the development of chronic viral hepatitis. The phenotype of these CD4-CD8-T ceils detected by flow cytometry is TCR αβ+CD3+CD4-CD8-CD25-CD28-CD30-CD44+. Key words: T-lymphocyte subsets;  Murine hepatitis virus;  Hepatitis, chronic