Bacterial Infections · Pathology

Toxic Shock Syndrome Toxin-1 (TSST-1) acts as a 'Superantigen.' What is the molecular consequence of this?

  1. Direct pore-mediated lysis of T-cell and NK-cell membranes
  2. Cross-links MHC class II and TCR Vβ, triggering a cytokine storm
  3. Blocks B-cell maturation into antibody-secreting plasma cells
  4. Blocks acetylcholine release at the presynaptic neuromuscular junction
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Correct answer: Cross-links MHC class II and TCR Vβ, triggering a cytokine storm

Superantigens bypass the normal antigen-processing pathway by binding directly to the outer surface of MHC class II molecules and the V-beta chain of T-cell receptors. This activates up to 20% of the body's T-cells, leading to a massive 'cytokine storm' (TNF-alpha, IL-1, IL-6).

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