Current information on the immunologic status of occult hepatitis B infection.

Hepatitis B is one of the most frequently occurring posttransfusion infections. Occult hepatitis B (OB) is a form of hepatitis B in which, despite the presence of hepatitis B virus (HBV) DNA in the serum and hepatocytes of a carrier, hepatitis B surface antigen is absent. In addition to the risk of transfusion of infection, OB can lead to cirrhosis, hepatic cancer, and reactivation of the viral duplication process in the carrier. The mechanisms responsible for progression of OB are yet to be clarified; however, some investigators have suggested that genetic and immunologic variables may play a significant role in the resistance of some individuals and sensitivity of other patients. This review addresses the current information regarding immunologic status of OB-infected patients.