Detection Of CD₄～+CD₂₅～+T Cell In Patients With Viral Hepatitis And Its Relationship With Subpopulation Lymphocytes

CD₄⁺CD₂₅⁺T cell is a regulatory T cell, which plays a role of immunity inability and immunity suppressive. In vivo it plays a role of sustaining homeostasis and autoimmunity tolerance. CD₄⁺CD₂₅⁺regulatory T cells can be produced in the thymus while naturally selecting of CD4+ T cells. The proportion of CD₄⁺CD₂₅⁺T cells remains constant in the population of CD4+ thymocytes. These cells are selected as a portion of the natural repertoire of CD4+ T cells.CD₄⁺CD₂₅⁺ regulatory T cells express CTLA-4 (Cytolytic T - lymphocyte - associated antigen-4) and TGF-β(transforming growth factor–beta), dosen't produce IL-2,IL-4, IL-5, IL-13 and interferon gamma (INF-γ), and produces a little IL-10. CD₄⁺CD₂₅⁺regulatory T cells exerts their suppressive function via inhibition of IL-2R alpha-chain in target T cells, such as CD4+T cell, CD8+ T cell and DC cell.The CD₄⁺CD₂₅⁺T cells inhibit the CD4+T cell proliferation and activation; it can also decrease the cytokines which produced by CD4+T cells. The function of CD8+ T cell can be inhibited by CD₄⁺CD₂₅⁺T cells by producing perforin, granzyme and IFN-gamma at CD8+ T cell transform and impairing CD8+ T cell cytotoxicity.Recently CD₄⁺CD₂₅⁺T cell have been ardently researched in the autoimmune disease, tumour and organ transplantation, though the study is preliminary in hepatitis C on abroad. However, it doesn't be studied on chronic hepatitis B, liver cirrhosis and severe hepatitis overseas or inland.Purpose: To probe its role in pathogenesis of liver diseases, the level and evolution of CD₄⁺CD₂₅⁺T cell in peripheral blood was detected in the patients with chronic hepatitis B, liver cirrhosis and severe hepatitis, and its relationship with subpopulation lymphocytes were evaluated.Methods: CD₄⁺CD₂₅⁺T cell, CD4+T cell and CD8+T cell in peripheral blood were detected by four-colour flow cytometry in 30 patients with chronic hepatitis B, 30 patients with liver cirrhosis and 30 patients with severe hepatitis. HBV-DNA was quantified by PCR method. Statistical analysis was performed by SPSS 12.0 version.Results: The mean of CD₄⁺CD₂₅⁺T cell was 7.39% in chronic hepatitis B patients, 6.47% in patients with liver cirrhosis and 7.53% in severe hepatitis patients, which were higher than that of healthy controls (4.06%, P<0.01, P<0.05, P<0.01). Percentage of CD4+ T cell was meanly 38.12% in chronic hepatitis B, which was lower than that of healthy controls (vs. 45.07%, P<0.01), liver cirrhosis 39.63% (vs. 45.07%, P<0.05), severe hepatitis 30.44 %( vs. 45.07 %, P<0.01).31.04% CD8+ T cell was found in chronic hepatitis B group, and the difference was not significant in compare to healthy controls( 29.58%, P>0.05). 32.25% CD8+T cell in severe hepatitis group was signicantly higher than that of healthy controls (29.58%, P< 0.05). The ratios of CD4+/CD8+ in peripheral blood of patients with severe hepatitis (1.11) and chronic hepatitis B(0.98) were less than the ratio in healthy controls(1.44, P<0.01). The levels of CD8+ T cell and CD₄⁺CD₂₅⁺T cell had no significant differences between patients with chronic hepatitis B and sever hepatitis.Conclusion: CD₄⁺CD₂₅⁺T cell in the peripheral blood was remarkably increased in the patients with chronic hepatitis B, liver cirrhosis and severe hepatitis, especially severe hepatitis. CD4+ T cell was reduced and CD8+ T cell was increased, and the ratios of CD4+/CD8+ T cells were lower. It is suggested that immunological function was disorganized in chronic hepatitis B and severe hepatitis. The abnormality of immunological function might result from abnormity of quantity and function of CD₄⁺CD₂₅⁺T cell.