Antibody and Th1/Th2-type responses in BALB/c mice inoculated with live or dead Echinococcus granulosus protoscoleces.

The aims of this study were to investigate whether a Th1- or a Th2-type response is stimulated in the first stages of experimental infection with Echinococcus granulosus, and to determine whether live or dead protoscoleces equally contribute to such Th1/Th2-type polarization. Live parasites stimulated the production of IL-10, IL-4 and IL-5 as early as week 1 postinoculation. The levels of IL-10 and IL-4 decreased towards week 4 p.i. and that of IFN gamma increased. The production of specific antibodies was characterized by high levels of systemic IgG1 and local IgM and IgG3 (measured in peritoneal lavages). In contrast, dead parasites induced elevated levels of IL-4, IFN gamma, IL-10 and IL-5 on week 1 postinoculation followed by a decrease of IFN gamma and an increase of IL-4. Low levels of specific antibodies were stimulated by dead parasites both systemically and in the peritoneal cavity. These results show that E. granulosus infection induced an early Th2-type response and that live parasites stimulated stronger antibody responses than dead parasites. In addition, they strongly suggest that both phenomena were modulated by live protoscoleces.