IgG Subclass Distribution of Hepatitis B Surface Antigen Antibodies Induced in Children with Chronic Hepatitis B Infection after Interferon‐α Therapy

The IgG subclass distribution of antibody to hepatitis B surface antigen (anti-HBs) was investigated in 19 children with chronic active hepatitis B infection who showed a complete serological seroconversion after interferon-a therapy. Determinations were done 6 and 12 months after treatment. Our results showed no selectivity in anti-HBs synthesis among IgG subclasses. All 4 IgG isotypes were involved in the response, with similar percentage contributions, on average, of IgG1 (35%), IgG3 (27%), and IgG4 (28%), followed by IgG2 (10%). IgG4 became the second most dominant isotype at the end of observation. These results are in contrast to those found after natural seroconversion, in which anti-HBs was highly restricted to neutralizing IgG1 and IgG3, with only a minor contribution from IgG2 and IgG4. It is postulated that analysis of the specific profiles of IgG subclasses may be of value for the estimation of the therapeutic efficacy of recombinant interferon-a used and may be helpful in choosing more-effective treatment. Chronic infection with hepatitis B (HB) virus can occur in children at any age and may lead to chronic hepatitis, liver cirrhosis, or hepatocellular carcinoma during childhood or adulthood [1]. Suppression of viral replication and modulation of the immune responses can prevent disease progression and decrease the severity of liver damage. Thus, the development of an effective therapy against HB virus infection seems to be a high priority. Interferon (IFN)‐a, a molecule that combines antiviral properties with the capacity to modulate the cellular immune response by its effects on the cytokine network [2], was proposed for the treatment of chronic HB »20 years ago [3]. Although its therapeutic use as an antiviral drug has increased significantly in recent years, a complete seroconversion