HBsAg-induced interferon-gamma secretion in T cells from asymptomatic HBsAg carriers and HB-immune donors in vitro.

Peripheral T lymphocytes obtained from asymptomatic carriers of hepatitis B surface antigen (HBsAg) and donors immune to hepatitis B (HB) through natural infection or vaccination were induced by the envelope protein (HBsAg) of the hepatitis B virus (HBV) into secretion of interferon-gamma (IFN-gamma) in vitro. The kinetics of the IFN-gamma response varied between individuals, but was constantly found to be biphasic, with an early peak attained after 12 hr-4 days and a late peak after 5-8 days of antigen stimulation. The early release of IFN-gamma activity was antigen-specifically induced, as it was in T cells from HB-immune and asymptomatic carriers of HBsAg but not HB-susceptible controls. The second peak of HBsAg-induced IFN-gamma secretion was induced in all three donor groups and the kinetics of IFN-gamma release were similar to that of the mitogen phytohemagglutinin(PHA)-induced IFN-gamma production in similarly prepared T-cell cultures. Thus the late burst of IFN-gamma activity seems to result from a mitogenic property contained within the envelope material of HBV. The mitogenic response was three- to fivefold higher for 4/7 asymptomatic carriers of HBsAg compared to HB-immune donors and HB-susceptible controls, indicating that some patients with chronic asymptomatic carriership of HBsAg exhibit enhanced mitogenic responses to HBsAg.