Figure 1.

Binding of Escherichia coli enterotoxin B subunit (EtxB) to A20 cells. Cells (1 × 10⁶/ml) were incubated for 20 min on ice with 1–60 µg/ml of EtxB in Hanks' balanced salt solution (HBSS) containing 0·01% azide. Cells were subsequently washed and labelled with polyclonal rabbit anti-EtxB followed by biotin-goat anti-rabbit for 30 min on ice. After further washing, the cells were labelled with ExtrAvidine-fluorescein isothiocyanate (FITC) conjugate and analysed by flow cytometry. Control cells were incubated with the markers, but in the absence of EtxB (thin line). The data represent two independent experiments. CV, constant of variance; GM, geometric mean.