Staph. aureus produce a superantigen contributes to massive disease caused cytokines that are released from polyclonal T- cell activation. Which one of the following best fits this description of a superantigen?
Correct Answer: Toxic shock syndrome toxin
Description: Superantigens can bind to major histocompatibility (MHC) class II molecules outside the peptide- bonding cleft, as well as to the T-cell receptor. Superantigen binding stimulates the release of large amounts of cytokines, including interleukin I and tumor necrosis factor. This mechanism is caused by stimulation of a high percentage of the pool of T lymphocytes (poly clonal activation) and explains to a large extent the pathogenesis of diseases caused by organisms with superantigens. Staphylococcus aureus produces both toxic shock syndrome toxin and enterotoxins (food poison ing), which exhibit the superantigen characteristics. Although toxic and harmful, exfoliative toxin, protein A, coagulase, and beta hemolytic hemolysin respond as regular antigens in the immune response and are specific in their destructive action in the body. Exfoliative toxin includes at least two proteins that cause the generalized desquamation seen in the scalded skin syndrome. Protein A nonspecifically binds to the Fe poion of munoglobulin G molecules and pre vents complement attachment and activation. Coagulase clots citrated plasma with the help of a serum factor, and probably assists in the development of the abscess lesion. S. aureus produces several hemolysis, or exotoxins. They damage- erythrocytes, platelets, and other cells in the body.
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