<s>[INST] context: Superantigens

 Certain species of infectious microorganisms produce powerful,

immunostimulatory and disease-causing toxins called superantigen, so called because of their ability' to a polyclonally active large fraction ( up to 20% ) of T cell population.

 Superangens are potent acvators of T-lymphocytes.
 Superangens smulate very large numbers of T cells, without relaon to their epitope specificity'.

This leads to an excessive and dysregulated immune response with release of cytokines IL - 1, IL - 2, TNF - α and IF - γ.

Conventional antigens bind to MHC class I or II molecules in the groove

of the β dimer (T cell receptor). In contrast, superantigen bind directly to the lateral portion of TCR β chain and MHC class II β chain, and stimulate T cells solely on γ β gene segment utilized
independent of the D, J and γ aα - sequences present → γ β restricted T cell mitogens.

Superantigens are capable of giving up to 20% of the peripheral T-cell pool,

whereas conventional antigens activate < 1 in 10, 000.

 Examples of superantigen Staphylococcal toxic shock syndrome toxin □ Certain nonhuman retroviral proteins,

Staphylococcal enterotoxins □ Yersinia pseudotuberculosis Staphylococcal exfoliative (erythrogenic) toxin □ Mycoplasma arthritis. Streptococcal toxic shock syndrome toxin □ Mouse mammary tumor virus. [/INST] question: Which of the following is a superantigen | options: A: Cholera toxin B: Diphtheria toxin C: TSST D: Vero-cytoxin | answer: C </s>