Maturation of macrophages from peripheral blood monocytes in Kawasaki disease: Immunocytochemical and immunoelectron microscopic study

Kawasaki disease (KD) is regarded as a cytokine-associated disorder, Despite intensive investigation into the etiology of KD, this remains unclear, although monocytes and macrophages are thought to play an important role, We examined peripheral blood monocytes using a monoclonal antibody, PM-PK, which recognizes mature macrophages but not monocytes, This study was conducted in 12 patients with KD, three patients with sepsis and 12 control subjects. Approximately 8% of whole peripheral blood monocytes from patients with acute KD were observed to be PM-2K positive, Approximately 15-20% of peripheral blood CD14(+) monocytes from these patients were positive for PM-2K antibody (as determined by immunoelectron microscopy), PM-2K-positive monocytes had significantly fewer numbers of intracytoplasmic peroxidase-positive granules than monocytes from control subjects. In contrast, PM-PK-negative monocytes from patients with acute KD had a significantly greater number of peroxidase-positive granules in the cytoplasm than in those from controls, Monocytes from patients with sepsis displayed PM-2K immunocytochemical staining, similar to that in monocytes from patients with KD, These results suggest that during the acute stage of KD, monocytes partly differentiate into macrophages in the peripheral circulation.