HBsAg-specific humoral and cellular immune responses in children and adolescents 8–14 years after vaccination against hepatitis B

In 1995, universal hepatitis B vaccination of infants was established in Germany. In this pilot study we examined antibody concentrations to hepatitis B surface antigen (anti-HBs) in children and adolescents 8–14 years after basic immunisation. Participants with anti-HBs concentrations lower than 10 IU/l received a booster vaccination. On the day of revaccination and 10 days later blood samples were taken and lymphocytes were isolated for analysis of cellular immunity. Furthermore, the humoral immune response was also analysed on day 10 after revaccination. Of the 285 children and adolescents enrolled in the study 132 (46,4%) were anti-HBs negative (anti-HBs below 10 IU/l). 85 of these participants were revaccinated, and 80 of them showed an anamnestic antibody response on day 10. Cellular immune responses were analysed in 39 of the revaccinated participants by ELISPOT for IFNγ and IL–5 using a two-coloured IFNγ/IL–5 Fluorospot assay. In poor antibody responders (anti-HBs <100 IU/l) a specific cellular response could not be detected. However, a number of children with an anti-HBs titer of at least 100 IU/l after revaccination were positive in the Fluorospot test: 37,5% of participants with 100–1000 IU/l, 20% of those with 1000–10000 IU/l and all with anti-HBs >10000 IU/l showed specific cytokine releasing cells. Interestingly, IL–5 used to be the better read-out parameter compared to IFNγ. Our results show that nearly half of individuals vaccinated in early childhood lose specific antibodies within 8–14 years, but more than 90% of them showed the presence of an immunological memory by prompt anti-HBs response after revaccination. Specific cellular responses were detectable only after revaccination and only in participants with higher anti-HBs values (>1000 IU/l).

HBV - IFNgamma - IL-5 - adolescents - cellular immune response - fluorospot - humoral immune response - infants - revaccination - vaccination