Platelet immune complex interaction in the pathogenesis of Kawasaki disease.

We have shown that the thrombocytosis which occurs in the 3rd and 4th week of Kawasaki disease is associated with the appearance in the circulation of platelet aggregating factors detected by the PAT test. These factors induce aggregation and serotonin release from normal platelets. The aggregation can be blocked by EDTA and Prostacyclin. The aggregating factor appears to be of high molecular weight, and its activity was lost following fractionation at low pH. The platelet aggregating activity was significantly associated with the presence of IgG immune complexes, and these features suggest that IgG immune complexes are responsible for the platelet aggregating activity.