Long-term persistence of T cell memory to HBsAg after hepatitis B vaccination

AIM:To determine if the T cell memory to HBsAg can persist for a long time after hepatitis B (HB) vaccination.METHODS: Thirty one vaccine recipients who werehealthcare workers (18 females and 13 males aged 34-58 years) from Utrecht University Hospital, Netherlands, and had previously received a standard course of vaccination for hepatitis B were investigated and another 9 unvaccinated healthy volunteers from the same hospital were used as the control.Blood samples were taken just before the experiment to test serum anti-HBs levels and the subjects were classified into different groups according to their serum titers of antiHBs and vaccination history.Their peripheral blood mononuclear cells (PBMC) were isolated from freshly heparinized venous blood and the proliferative response of T lymphoo/tes to the recombinant hepatitis B surface antigen (HBsAg) was investigated.RESULTS: Positive serum anti-HBs was found in 61.3%(19/31) vaccine recipients and a significant in vitro lymphocyte proliferative response to recombinant HBsAg was observed in all the vaccinees with positive anti-HBs.Serum anti-HBs level≤10IU/L was found in 38.7% (12/31) subjects.In this study, we specially focused on lymphocyte proliferative response to recombinant HBsAg in those vaccine recipients with serum anti-HBsAg less than 10IU/L.Most of them had received a standard course of vaccination about 10 years before. T lymphocyte proliferative response was found positive in 7 of the 12 vaccine recipients.These results confirmed that HBsAg-specific memory T cells remained detectable in the circulation for a long time after vaccination,even when serum anti-HBs level had been undetectable.CONCLUSION: The T cell memory to HBsAg can persist for at least 10 years after HB vaccination. Further booster injection is not necessary in healthy responders to HB vaccine.

Is a low dose of hepatitis B vaccine enough for a rapid vaccination scheme?

AIM: To determine whether or not a low dose of HB vaccine can be effectively used in the rapid vaccination.METHODS: Rapid vaccination (0, 1, 2 months) with low dose (5 μg) or routine dose (10 μg) HB vaccine was studied in 250 subjects (130 school children and 120 university students). Serum from all the participants was tested for HBsAg, anti-HBs and anti-HBc at 1, 3 and 7 months after the first dose of vaccination and all subjects were serum HBV marks negative before the vaccination. Non-responders to a complete initial vaccination from university students were given an additional vaccination with 10 μg of HB vaccine and their serum anti-HBs was tested again one month later.RESULTS: One month after the third dose of vaccination (third month) sero-conversion rates and geometric mean titer (GMTs) were significantly (P＜0.01) higher in the routine dose (resp. 89 % and 106.8) than in the low dose group (resp. 72 % and 59.5). Sero-conversion rates and GMTs were maintained stable for another 4 months in both groups.After an additional vaccination to non-responders with 10 μg HB vaccine, 17/23 subjects (13/15 from those vaccinated with 5 μg vaccine and 4/8 from those vaccinated with 10 μg vaccine) became anti-HBs positive, yielding similar seroconversion rates for both dose groups.CONCLUSION: Higher sero-conversion rates and GMTs were reached in those vaccinated with 10 μg HB vaccine than in those vaccinated with 5 μg HB vaccine after a comp^te vaccination with a 0, 1, 2 month scheme. But the subjects vaccinated with 5 μg vaccine can also reach the similar sero-conversion rate after an additional vaccination.