The IgG subclass profile of anti-HBs response in vaccinated children and children seroconverted after natural infection

The IgG subclass profiles of anti-HBs antibodies were investigated in 30 ch ildren who had recovered from acute hepatitis B and 40 children vaccinated against hepatitis B virus (HBV) with Engerix B. After natural seroconversio n the mean geometric value of anti-HBs titres was ca 41-fold lower than at the peak of response in vaccinees, and specific antibodies were highly rest ricted to IgG1 subclass followed by IgG3 with only a minor contribution of IgG2 and IgG4. Conversely, in children immunized with recombinant HBsAg, IgG1 and IgG3 dom inated after two doses of vaccine and 1 month after the third injection but the response was less selective and more variable. One year after vaccinat ion IgG4 anti-HBs antibodies became the second dominating isotype. Signific ant statistical differences in the profiles of IgG anti-HBs were observed w hen the age and maturity of humoral response were considered. While childre n vaccinated below 5 years of age responded mainly with IgG1 and IgG3 subcl asses, older children (>5 years) showed a high individual variability in th e specific profiles with a high contribution of IgG4, We concluded that vac cination at a younger age leads to the production of antibody subclasses wh ich are more effective for virus neutralization. (C) 2000 Elsevier Science Ltd. All rights reserved.