HBV-specific lymphoproliferative and cytokine responses in patients with chronic hepatitis B

Background/Aims:
Hepatitis B virus specific T cell reponses are crucial for viral elimination but their nature is not fully understood.
Methods:
We studied the regulation of proliferation and cytokine production after antigenic stimulation in peripheral blood mononuclear cells from chronically HBV-infected patients and subjects with natural immunity after recovery from an acute infection. Proliferation and production of interferon-γ, IL-10 and tumor necrosis factor-α were determined after stimulation with HBcAg, HBeAg or HBsAg in the absence or presence of IL-12 or neutralizing antibodies to IL-12, interferon-γ, IL-4, IL-10 or tumor necrosis factor-α.
Results:
Upon stimulation with HBcAg or HBeAg, peripheral blood mononuclear cells from chronic hepatitis B virus patients displayed a clear class-II restricted proliferative response (SI greater than 2.5). Both interferon-γ (less than 50 IU/ml) and IL-10 levels up to 600 pg/ml were detected. Proliferative or cytokine responses to HBsAg were very weak or absent. Addition of IL-12 to HBeAg-stimulated cultures increased the production of interferon-γ to more than 200 IU/ml in all patients and slightly increased the production of IL-10. Neutralization of IL-10 increased the HBeAg-induced interferon-γ production but had no effect on tumor necrosis factor-α production. Addition of anti-IL-4 or anti-tumor necrosis factor-α had no significant influence on proliferation or cytokine release. Importantly, in both chronic hepatitis B virus patients and naturally immune subjects, IL-12 induced proliferative and interferon-γ responses in peripheral blood mononuclear cells stimulated with HBsAg.
Conclusions:
Our data indicate that peripheral blood mononuclear cells from chronic hepatitis B virus patients proliferate and produce interferon-γ and IL-10 upon HBeAg but not upon HBsAg stimulation. IL-12 augments the HBeAg-induced responses and, additionally, provokes proliferation and interferon-γ production in HBsAg-stimulated cultures.