Which property of a bacterial toxin is proposed in Kawasaki disease?

• A. Superantigen properties
• B. Enzymatic degradation of collagen
• C. Induces autoantibodies
• D. Direct bacterial invasion

Answer: (A)

Kawasaki disease is thought to involve an immune system explosion driven by a toxin with superantigen-like properties. Superantigens don’t require a normal, specific antigen presentation; they bind directly to MHC class II on antigen-presenting cells and to the Vβ region of T-cell receptors. This causes massive, nonspecific T-cell activation and a big surge of cytokines, producing widespread inflammation. That pattern matches Kawasaki’s fever and multisystem inflammation, including effects on the heart vessels.

Enzymatic degradation of collagen would imply a toxin that directly chews up connective tissue, which isn’t the described mechanism in Kawasaki disease. Direct bacterial invasion would mean the bacteria themselves are present in tissues causing damage, whereas Kawasaki is better thought of as an immune-mediated process rather than a straightforward infection of the vessels. Inducing autoantibodies might occur in various conditions, but the strongest and most discussed toxin property for Kawasaki is superantigen-like activity that provokes broad T-cell activation and cytokine release.