Circulating CD3+HLA-DR+ Extracellular Vesicles Are Not Increased in the Acute Phase of Kawasaki Disease

Kawasaki disease (KD) is an acute inflammatory illness with unknown etiology. We prospectively measured novel T cell–derived CD3+HLA-DR+ extracellular vesicles (EVs), which specifically reflect T cell activation in the acute phase of KD, after IVIG treatment, and in convalescence phase in 35 newly diagnosed KD patients. There was little increase in CD3+HLA-DR+ EVs before IVIG treatment and no significant change after IVIG treatment and in the convalescence phase. This result supports the view that the involvement of acquired immunity in the pathogenesis of KD is less likely.