Considerable decrease in antibodies against hepatitis B surface antigen following kidney transplantation

BackgroundImmunization against hepatitis B virus (HBV) in kidney transplantation (KT) candidates and recipients is recommended. If anti-HBV surface antigen antibody (anti-HBsAb) titer of 10 IU/L is admitted to be protective, the optimal threshold, at and after KT, is unknown. In addition, the natural evolution of anti-HBsAb titers after KT is not reported.ObjectivesTo describe rates of protective immunity to HBV at time of KT (baseline) and evolution of anti-HBsAb titers during the following year.Study designWe retrospectively analyzed HBV serology at baseline, 15 days, and 4 and 12 months post-KT. No patient received vaccination during the study period, but information about previous vaccination was unavailable.ResultsAt baseline 80% of 141 recipients had anti-HBsAb titer ≥10 IU/L. Among these 113 patients, 84 had subsequent HBV serologies at day 15 and month 4, and 67 had also serology at month 12. At month 12, 25% of patients had lost protective anti-HBsAb titers (p < 0.001). The duration of protective anti-HBsAb titers was significantly longer when the initial titer was ≥ 100 IU/L versus <100 IU/L (log-rank test p < 0.0001). Protective titers at month 12 persisted in 93% of patients with initial titer ≥100 IU/L compared to 33% with 10–100 IU/L titer (p < 0.0001). In contrast, duration of protective titers did not differ according to the anti-HBV core antigen antibody status at baseline.ConclusionsDespite a high prevalence of protective anti-HBsAb titer at KT, the loss of protective immunity during the following year was considerable, particularly when initial anti-HBsAb titer was <100 IU/L.