Interleukin-17A correlates with interleukin-6 production in human cystic echinococcosis: a possible involvement of IL-17A in immunoprotection against Echinococcus granulosus infection.

Hydatidosis is a parasitic disease caused by the development, in humans and other mammals, of the larval form of Taenia, Echinococcus granulosus. It is one of the world's major zoonotic infections. This study aimed to examine interleukin-6 (IL-6), interferon-γ (IFN-γ) and interleukin-17A (IL-17A) production in patients with cystic echinococcosis (CE), and the role of IL-17A in the modulation of the immune response against the extracellular parasite, E. granulosus. A relationship between IL-6, IL-17A production and C reactive Protein (CRP) levels was also assessed. IL-6, IFN-γ, IL-17A and CRP production were determined in serum from Algerian hydatid patients. Cytokine production was also measured in supernatants from cultures of peripheral blood mononuclear cells (PBMCs) from hydatid patients stimulated by a major parasitic antigen (antigen-5). The increased activity of IL-6, IFN-γ and IL-17A were observed in most serum samples from patients. In contrast, healthy controls showed only minor levels. Similarly, high levels of CRP were detected. Our in vitro results indicate a positive correlation between IL-6, IFN-γ and IL-17A production in PBMC culture supernatants. However, IL-6, IFN-γ and IL-17A activity was low in serum and supernatants of PBMC cultures from relapsing patients, and there was no evidence of an immune response against parasitic antigen. Collectively, our results show that IL-17A was produced during human cystic echinococcosis, and was involved in the host defense mechanisms against the extracellular parasite E. granulosus. Our data suggest that IL-17A plays an immunoprotective role in this parasitic, helminth infection.