Fig. 2.

Schistosome eggs suppress innate immune responses and are incapable of disrupting epithelial cell layers in vitro. (a,b) Dendritic cells from C57BL/6 mice were generated from bone marrow cells using granulocyte–macrophage colony-stimulating factor (GM-CSF). After 7 days, dendritic cells (DC) (2 × 10⁵) were co-cultured with 400 viable eggs for 2 h. Thereafter, cells were stimulated with either Pam₃Cys, lipopolysaccharide (LPS), R848 or cytosine–phosphate–guanosine (CpG). After an additional 48 h, culture supernatants were removed and analysed for the production of tumour necrosis factor (TNF) (a) and interleukin (IL)-6 (b) via enzyme-linked immunosorbent assay (ELISA). Bars represent mean ± standard deviation (s.d.) of three pooled experiments. (c) Eggs were placed with or without TNF into the upper chamber of an in-vitro system resembling the intestinal epithelium. Epithelial integrity was then monitored at the indicated time-points by measuring the resistance of the epithelial cell layer [transepithelial electrical resistance (TER)]. Symbols represent pooled data from two independent assays. Asterisks indicate significant differences using one-way analysis of variance (anova) (**P < 0·01; ***P < 0·001).