HUMORAL RESPONSE TO INFLUENZA HEMAGGLUTININ - OLIGOCLONAL SPECTROTYPEAND FAILURE OF THYMOPENTIN AS IMMUNOADJUVANT

Influenza remains a serious cause of illness and death among certain p opulations. Influenza vaccines in use at present are of limited effect iveness due to the high variability of the virus, and trials all over the world are in progress to enhance their immunogenicity. Conflicting results, in fact, have been reported about the immune response to inf luenza vaccination in diverse populations. In this paper we analyzed t he antibody response to the hemagglutinin (HA) of the H3N2 A/Shangai 1 6/89 strain, which was included into the trivalent 1991-92 influenza v accine, in four groups of subjects: 8 healthy young, 13 human immunode ficiency virus (HIV)-infected and 37 elderly healthy people, 9 of whom were treated with thymopentin (TP-5). Our results show levels of anti -HA IBG before vaccination in HIV: infected and elderly people signifi cantly lower than those of normal young subjects. After vaccination, H IV-infected and elderly healthy people showed a significant increase o f specific antibodies, whereas a failure in the specific response in n ormal young subjects was observed, thus differences among the groups w ere no longer present. Moreover, the spectrotypic analysis of antibody response, by isoelectric focusing and reverse blotting, showed oligoc lonal but polymorphic pattern in the majority of subjects, irrespectiv e of the group, and more frequently lack of expansion of the spectroty pe after vaccination, thus demonstrating the lack of the recruitment o f antigen-specific B cells. Finally, the treatment with TP-5 did not i nfluence the outcome of the vaccination in the group of elderly people . These results further emphasize the limited immunogenicity of influe nza vaccination and the inefficacy of TP-5 as immunoadjuvant, in this model of vaccination.