ANTIBODY-RESPONSE TO INFLUENZA, TETANUS AND PNEUMOCOCCAL VACCINES IN HIV-SEROPOSITIVE INDIVIDUALS IN RELATION TO THE NUMBER OF CD4+ LYMPHOCYTES

Objective: To establish when the formation of antibodies against T-lym phocyte-dependent and -independent antigens is impaired during HIV inf ection. Design: Prospective study on antibody formation before and 30 days and 60 days after vaccination with tetravalent influenza vaccine, tetanus toxoid and pneumococcal vaccine; booster with influenza vacci ne was administered 30 days after initial vaccination. Setting: Outpat ient clinic of University Hospital Leiden. Participants: Fifty-one HIV -infected individuals and 10 healthy controls. Results: In HIV-infecte d individuals with < 100 x 10(6)/l CD4+ lymphocytes almost no influenz a antibodies were formed; CD4+ counts between 100 and 300 x 10(6)/l co rrelated with suboptimal antibody formation; CD4+ counts greater-than- or-equal-to 300 x 10(6)/l yielded more individuals with protective ant ibody titres. Thirty days after vaccination, protective antibody titre s against the four influenza strains had been achieved in 24% of all H IV-infected individuals for A/Beijing (H3N2) (controls, 90%), 59% for A/Taiwan (H1N1) (controls, 80%), 18% for B/Beijing (controls, 30%) and 37% for B/Panama (controls 90%). Booster vaccination after 1 month di d not increase antibody levels. Anti-tetanus toxin antibody formation, which is also T-lymphocyte-dependent, was correlated with the number of CD4+ lymphocytes. After pneumococcal vaccination (T-lymphocyte-inde pendent), normal antibody formation was observed in HIV-infected indiv iduals, including those with low CD4+ counts. Conclusions: Influenza v accination should not be administered to HIV-infected individuals with CD4+ counts < 100 x 10(6)/l; pneumococcal vaccination can be offered to all HIV-infected individuals and a tetanus toxoid booster should be administered when indicated.