Cellular and humoral immune responses in haemophiliacs after vaccination against tick‐borne encephalitis

Abstract

S ummary . The primary immune response to a viral antigen (tick‐borne encephalitis, TBE) has been determined in haemophiliacs. Twelve HIV‐negative and four clinically asymptomatic, HIV‐positive haemophiliacs as well as 16 age‐matched healthy controls were included in the study. Antibody responses after TBE vaccination were comparable in HIV‐negative haemophiliacs and controls: however, antibody titres in HIV‐infected haemophiliacs were significantly lower after completion of the three‐dose vaccination schedule (geometric mean reciprocal antibody titres (SEM): controls. 193 (1.37), HIV‐positive haemophiliacs. 13 (2.18), P < 0.005). TBE vaccination failed to induce a T cell proliferative response in the HIV‐positive haemophiliacs. While in HIV‐negative patients the antigen‐specific lymphoproliferative responses after primary and one booster vaccination were comparable to those of the controls, cellular responses were decreased in HIV‐negative haemophiliacs following a second booster immunization 19 months after primary immunization ( 3 H‐thymidine incorporation, delta dpm, mean ± SEM: controls, 34662 ± 7129, HIV‐negative haemophiliacs, 14339±7420, P <0.005). As the protective mechanisms for TBE infection are not yet completely understood, further work will be necessary to determine whether the decreased capacity to mount a sufficient long‐term cellular memory response in HIV‐negative haemophiliacs might be important for the protective effect of TBE vaccination in this population.