FIG. 2.

Antibody neutralization of epsilon-toxin cytotoxicity. Epsilon-toxin (2.5 CT₅₀ units) was incubated for 1 h at 37°C with serial dilutions of negative control antibodies (▪), anti-epsilon-toxin 4D7 (□), or anti-epsilon-toxin 5B7 (•). The toxin-antibody mixtures then were added to MDCK cell monolayers and incubated at 37°C for 16 h. Cytotoxicity was assessed by staining cells with the metabolic indicator MTT as described in Materials and Methods. Data represent the means and standard deviations for triplicate samples and are expressed relative to the staining of cells not treated with toxin.