The Window Period Between Hepatitis B e Antigen and Antibody in Chronic Type B Hepatitis

To examine the period between disappearance of hepatitis B e antigen (HBeAg) and appearance of anti‐HBe, 48 patients with clinicopathologically verified chronic B hepatitis were followed every 1 to 3 months after HBeAg clearance. Sera were tested by radioimmunoassay for HBeAg and anti‐HBe. Anti‐HBe appeared in days to years, mostly (78.7%) within 1 year, after disappearance of HBeAg. Only 40.5% of patients had an “e‐window” shorter than 1 month. Clinical and histological exacerbation preceding HBeAg clearance precipitated or accelerated appearance of anti‐HBe. Since the patients in the “e‐window” period were positive for DNA polymerase, it is suggested that the “e‐window” reflects relative insensitivity of the radioimmunoassay rather than absence of HBeAg/anti‐HBe. Therefore, HBeAg can reappear and clinical activity can relapse particularly during immunosuppressive therapy.