Ageing impairs parasite-specific antibody responses in cystic echinococcosis

Humoral immunity wanes during healthy ageing, increasing susceptibility to infections in the elderly. In this sense, information about parasite infections and human immunosenescence is scarce. Cystic echinococcosis (CE) is an infectious disease caused by the larval stage of the cestode parasite Echinococcus granulosus, whose prevalence in humans shows an increase with host age. Susceptibility to human CE has been associated with humoral immunity to some extent, and, therefore, we have here analysed the influence of host age on the serological profile of young, middle-aged and aged patients. Our results highlighted the detrimental influence of ageing on the intensity and quality of the antiparasite antibody response. Remarkable differences in serological profiles between young and aged individuals were observed. In this sense, through Principal Components Analysis, we identified aged patients as those exhibiting overall less intense antibody responses, mainly in isotypes/subclasses supposed to exert efficient antiparasite activities (eg IgE and IgG1). Thus, these humoral defects could at least partially explain the reported increase in CE prevalence among older individuals, as a weaker immune response in the elderly might facilitate the establishment and maintenance of the parasite infection. Finally, a possible association between age-dependent susceptibility to CE and host immunosenescence is discussed.