superantigen
Pronunciation: SOO-per-an-ti-jen
Microbial toxins that cause massive T-cell activation and cytokine release, implicated in pediatric toxic shock syndrome and food poisoning.
Full Definition
A class of antigens that bind simultaneously to MHC class II molecules and T-cell receptors outside the normal antigen-binding site, causing polyclonal T-cell activation and massive cytokine release. In pediatric medicine, superantigens are responsible for toxic shock syndrome caused by Staphylococcus aureus and Streptococcus pyogenes, as well as staphylococcal food poisoning. Unlike conventional antigens that activate small percentages of T cells, superantigens can activate up to 20% of T cells, leading to severe systemic toxicity.
Usage
Usage note: Always written as one word; refers specifically to the mechanism of action, not the severity of the antigen.
In Context
- "The staphylococcal superantigen triggered massive T-cell activation resulting in toxic shock syndrome." — infectious disease case report
- "Laboratory studies confirmed superantigen-mediated pathogenesis in the outbreak of food-borne illness." — public health investigation