[Infection due to hepatitis B virus and host immune response].

Cell mediated immunity (CMI) to hepatitis B surface antigen (HBs Ag) was investigated in patients who recovered from acute hepatitis B and in chronic carriers of the antigen, either with or without liver disease. The study was performed using leukocyte migration inhibition test and purified HBsAg. In antigen negative posthepatitis patients the frequency of cellular immunity to HBsAg (63.6%) showed a significant difference to controls. On the other hand, only one out of 5 antigen positive post hepatitis patients showed sensitisation to HBsAg; 4 of these cases had chronic hepatitis at liver biopsy. In HBsAg chronic carriers, with or without liver disease, the frequency of CMI to HBsAg was not significant to controls. A significant correlation was noted between inflammatory activity and inhibition of migration. The results suggest that a normal cellular immune response to HBsAg is necessary for the recovery from acute hepatitis B and for the clearance of the virus. In HBsAg chronic carriers this response seems to be absent or inadequate, leading to the state of healthy chronic carriers or to the evolution to HBsAg chronic hepatitis, respectively. The high frequency of CMI in HBsAg negative chronic active hepatitis, suggests that hepatitis B virus infection may play a role in the etiology of the disease.