Interaction of staphylococcal exfoliative toxin with concanavalin A

Treatment of mouse embryo fibroblasts (MEF) grown in vitro with purified staphylococcal exfoliative toxin (ET) increased the concanavalin A (Con A) agglutinability of MEF 3.5-fold over control cells. Possible explanations for this phenomenon were investigated. ET lacked proteolytic activity on denatured casein. Con A, however, was found to interact directly with ET as evidenced by the formation of precipitation in an agar gel diffusion plate and in increased turbidity in solution. This interaction was inhibited by alpha-methyl-d-glucopyranoside. The ability of Con A to precipitate with ET suggests that the toxin contains a carbohydrate component and that the carbohydrate associated with ET is branched rather than linear. An analysis of a purified preparation of ET indicated the presence of 9% carbohydrate and no lipid.