Neutrophilic involvement in the damage to coronary arteries in acute stage of Kawasaki disease

Background: There has been no morphological evidence that polymorphonuclear leukocytes (PMNL) infiltrate the coronary arterial lesions of acute Kawasaki disease (KD) patients, although clinical data indicate the activation of PMNL. Methods: The experimental materials consisted of eight autopsy patients who died during the acute phase of KD. Duration of the illness ranged from 6 to 32 days. The tissues were fixed and embedded in paraffin. Hematoxylin and eosin, elastica van Gieson and azan-Mallory stainings were performed for routine histological examination. In addition, antibodies to CD3, CD20, CD68 and neutrophil elastase were used for immunohistochemistry to identify infiltrating cells in arterial lesions. Results: The inflammatory cells that appeared in the coronary arterial lesions were mainly composed of macrophages in all patients. In addition, numerous neutrophils were also identified in the coronary arterial lesions of the patients who died 10 days after the onset of KD. Neutrophilic infiltration reached a peak earlier than the peaks of CD68+ macrophages, CD3+ T lymphocytes and CD20+ B lymphocytes. Conclusions: These results suggest that neutrophils are involved in the damage occurring to coronary arteries in the early stage of KD. Vasodilation might occur as a result of injury to vascular walls caused by neutrophils, as well as macrophages.