Kawasaki disease (KD), an acute vasculitis of infancy and early childhood, affords a unique opportunity to study acute endothelial cell (EC) damage in the setting of previously healthy arteries unaffected by underlying disease processes such as atherosclerosis, hypertension, or diabetes. KD is now the most common form of acquired heart disease in children in the United States and Japan (1,2). The vasculitis presents with clinical signs that include fever, rash, conjunctival injection, edema and erythema of the extremities, andmucosal erythema (3).Thevasculitis is self-limited, butwithout treatment, one in four children will develop coronary artery aneurysms occasionally accompanied by aneurysms of other mediumsized, muscular, extraparenchymal arteries (4). Echocardiography during the first 2 months after onset of fever is used to classify patients as having normal, dilated, or aneurismal coronary arteries. Long-term sequelae of the coronary artery aneurysms include ischemic heart disease and myocardial infarction. The acute inflammation can be abrogated in the majority of patients with a single dose (2 g/kg) of intravenous immunoglobulin (IVIG) and aspirin (80–100 mg/kg/day), which reduces the aneurysm rate to 3% to 5% (5).

The etiology of KD remains unknown, although an infectious cause is suspected based on seasonality and clustering of cases (2) and the similarity of clinical signs to other infectious diseases. In addition, the peak incidence in infants and children younger than 5 years, coupled with the rare occurrence of KD in adults and infants younger than 3 months of age, is consistent with infection with a widely disseminated agent that causes asymptomatic infection in most hosts and the acquisition of protective immunity and passage of transplacental antibodies.