Characterization of the immune response induced by a carbohydrate enriched fraction from Echinococcus granulosus protoscoleces in patients with cystic hydatid disease.

The serological and cellular immune response against a carbohydrate-enriched fraction of Echinococcus granulosus (E4+) was studied in a group of patients with cystic hydatid disease (CHD). The profile of IgG subclass against E4+ and the native non-enriched extract (protoscolex somatic antigen, PSA) were compared. A relatively higher ratio of IgG2:IgG4 was induced by E4+ than by PSA (12.4 vs 3.6 respectively). Serological data were associated with clinical parameters dealing with the outcome of disease. The expression of IgG1 and IgG4 subclasses against both of the antigens was associated with the progression of the disease. Interestingly, anti-PSA IgG4 was the only variable that was specifically associated with the stage of cysts (P < 0.04). Similar levels of IL-13 were evoked by peripheral blood mononuclear cells from patients with CHD when incubated with either of the antigens, while higher levels of IL-10 were obtained in supernatants from cells stimulated with E4+ (P < 0.029) than from those stimulated by PSA. Considerable amounts of IL-10 (median 60 pg/ml) were obtained in the supernatants of cells from healthy individuals incubated with E4+. Our results suggest a putative role for E4+ in immunoregulation during the course of infection with E. granulosus in humans.