Considering the amount of deposited eggs increased gradually with the elongation of the worms′life in vivo or with the development of schistosomiasis, we analyzed the ability of different concentrations (serially diluted from 40 μg/ml to 0.156 μg/ml) of SEA at attenuating IFN-γ-induced MHC class II expression. This evidence concerns the gene IFNG and schistosomiasis.