Echinococcus granulosus glycoconjugates induce peritoneal B cell differentiation into antibody-secreting cells and cytokine production.

Helminth parasite infections are associated with predominant Th2-type cytokine responses, and parasite glycoconjugates have been recognized as partially responsible for such immune bias. It has been proved that Echinococcus granulosus evokes a Th2-type cytokine pattern characterized by a high production of IL-4, IL-5, IL-6 and IL-10, and no or mild IFN-γ levels in animal models and in patients with cystic echinococcosis, respectively. Here, we show that E4(+) (a glycoconjugate-enriched fraction from E. granulosus protoscolex) stimulated the secretion of a high concentration of IL-6, followed by IL-10 and TNF-α by normal peritoneal B cells. We determined that E4(+) bound to the surface of peritoneal B cells and induced their activation and, also, triggered the differentiation of peritoneal B cells into IgM-, IgG2b- and IgG3-secreting cells in a T-independent way. Interestingly, the IgM released by E4(+) -stimulated peritoneal B cells from normal mice recognized protoscolex antigens. Results showed that, after the encounter with antigens from E. granulosus protoscolex, peritoneal B cells are a source of Th2-type cytokines and polyclonal antibodies, some of which recognize parasite antigens, suggesting that peritoneal B cells can condition the outcome of the infection.