FIG. 4.

The SLO mutant N402E does not induce the production of biologically active TNF-α. Mast cells were activated with the indicated concentrations of SLO or the SLO mutant N402E for 2 h, and a bioassay for biologically active TNF-α in the supernatants was performed. As an additional internal control, the biological activity of TNF-α was blocked by the addition of a neutralizing anti-TNF-α antibody (anti-TNF). Shown are the means of three experiments. The error bars represent standard deviations.