Toxic shock syyndrome caused by staphylococcus is due to -

The pyrogenic toxin superantigens are a family of small-molecular-size, structurally similar proteins that are responsible for two diseases: TSS and food poisoning. TSS results from the ability of enterotoxins and TSST-1 to function as T cell mitogens. Enterotoxins bind directly to the invariant region of MHC--outside the MHC class II groove. The enterotoxins can then bind T cell receptors the vb chain, and thisbinding results in a dramatic overexpansion of T cell clones (up to 20% of the total T cell population). The consequence of this T cell expansion is a "cytokine storm," with the release of inflammatory mediators that include interferon g, IL-1, IL-6, TNF-a, and TNF-b. The resulting multisystem disease produces a constellation of findings that mimic those in endotoxin shock; however, the pathogenic mechanisms differ. (Harrison's Principles of internal medicine, 20 th edition, page 1162)