In Kawasaki disease, which property of a bacterial toxin is thought to be involved in its etiology?

• A. Viral infection
• B. Bacterial toxin with superantigen properties
• C. Autoimmune reaction to heart tissue
• D. Genetic mutation

Answer: (B)

Kawasaki disease is thought to involve immune activation driven by a bacterial toxin that acts as a superantigen. Superantigens bind directly to MHC class II molecules and the Vβ region of T-cell receptors, causing broad, nonspecific T-cell activation. This massive T-cell response releases a storm of cytokines (like IL-1, IL-6, TNF-alpha, and IFN-γ), which can drive widespread inflammation of blood vessels, including the coronary arteries typical of Kawasaki disease. The idea fits with the clinical picture of systemic inflammation and vasculitis. Other options don’t reflect a toxin with the capacity to cause such widespread, non–antigen-specific immune activation.