T cell responses to hepatitis B surface antigen are detectable in non-vaccinated individuals

To evaluate, whether humoral hepatitis-B-vaccine non-responders also fail to mount a T cell response and to compare these results to normal vaccinees.Fourty-seven health care employees were enrolled in this study including all available non-responders (n = 13) with an anti-HBsAg titer10 kU/L and all available low-responders (n = 12) with an anti-HBsAg titer100 kU/L. Also, 12 consecutive anti-HBsAg negative pre-vaccination subjects were enrolled as well as 10 subjects (+7 from the vaccinated group) with titers1000 kU/L as controls. PBMC from all subjects were analyzed by IFN-gamma and IL-4 ELISPOT assays for the presence of hepatitis B surface antigen (HBsAg) reactive T cells.Non-responders and low-responders had no or only very limited T cell responses, respectively. Individuals responding to vaccination with the induction of a high anti-HBsAg titer showed a strong T cell response after the third vaccination. Surprisingly, these individuals showed response even before the first vaccination. T cell response to control antigens and mitogens was similar in all groups.Our data suggest that there is no general immune deficiency in non-/low-responders. Thus, we hypothesize that the induction of anti-HBsAg responses by vaccination is significantly dependent on the pre-existing T cell repertoire against the specific antigen rather than the presence of a general T cell defect.