Immunological memory in individuals who had lost protective antibodies after hepatitis B vaccination

Long-term protection after hepatitis B vaccination is dependent on the persistence of a strong immunologic memory. It has been shown that specific memory lasts for at least 10–15 years; its exact duration, however is not known. In search of reliable markers for an HBsAg-specific immunological memory we studied the cellular and humoral immune responses of 15 healthy individuals who were successfully vaccinated but had lost protective anti-HBs titers. To determine the reactivity of vaccine-induced HBsAg-specific T cells of both effector and memory phenotype we isolated CD4+/CD45RA+ and CD4+/CD45R0+ T cells. Cells…