Age is an important determinant in humoral and T cell responses to immunization with hepatitis B surface antigen.

The aging of the immune system, also named immunosenescence, affects vaccine responses. However, the onset of age-related immunosenescence has been uncertain, in particularly with regard to vaccine responses. Here, we show that the formation of antibodies in response to vaccination against hepatitis B virus infection was significantly reduced for donors with a mean age of 61 y compared with a group with a mean age of 33 y. Booster vaccination sero-converted the elderly donors, but only at a reduced level, while a stronger response was found for the group of young donors. Agreeing with these findings, the hepatitis B surface antigen-specific proliferative responses by donor-derived T cells were reduced for the elder donors. Interestingly, the association between expression of the adhesion molecule CD62L (L-selectin) on naïve and central memory T cells and the formation of antigen-specific antibodies differed significantly between younger and elder donors. This finding corresponds well with the observation made previously that CD62L gene ablation in animals alters the formation of antigen-specific antibodies. We suggest that a complex interplay between the expression of CD62L and its ligands is a determinant in early-age immunosenescence affecting the response to HBV vaccination.