The in vitro effect of interferon-alpha 2a on CD95 expression of T cells in hepatitis B

In chronic hepatitis B, apoptotic rate of peripheral cytotoxic T cells may be related with hepatocyte injury. We aimed to investigate Fas (CD95) expression of peripheral cytotoxic T cells and to show the in vitro effect of interferon-alpha 2a on Fas expression and apoptosis.

The study group consisted of 17 patients with chronic hepatitis B and control group consisted of 10 healthy subjects. Apoptotic cells were identified by flow-cytometric assay using Annexin V and propidium iodide. We used monoclonal antibodies stained by direct immunofluorescent method to show surface molecules. CH-11 monoclonal antibodies were used as anti-Fas antibodies.

Basal expressions of CD95 and CD8+ CD95+ in the peripheral mononuclear cells were higher in chronic hepatitis B patients than controls. In vitro treatment with interferon-alpha 2a increased the percentage of CD8+ 95+ peripheral mononuclear blood cells in controls; this effect was less remarkable in patients with chronic B hepatitis, and the difference was not statistically significant. The number of apoptotic cytotoxic T cells also increased in 5 subjects of the study group and 3 subjects of controls; the percentage of CD95+ cells increased in 7 of 17 patients and 8 of 10 controls. The percentage of CD8+ 95+ cells and the apoptotic rate of CD8+ cells were not different between study group and controls after combined treatment with interferon-alpha 2a and monoclonal stimulating anti-Fas antibodies.

We suggest that interferon-alpha 2a does not induce Fas-dependent apoptosis in CD8+ peripheral T cells of the patients with chronic hepatitis B, and CD95 molecules on peripheral cytotoxic T cells might be defective.