Activation of peripheral blood monocytes and macrophages in Kawasaki disease: ultrastructural and immunocytochemical investigation.

Monocytes/macrophages are considered to play an important role in the pathogenesis of Kawasaki disease (KD). However, the morphological and immunocytochemical features of the cells in acute KD have not been investigated. The ultrastructural and immunocytochemical characteristics of peripheral blood CD14+ monocytes/macrophages sorted by a magnetic cell sorter (MACS) during the course of KD were, therefore, studied to evaluate their role in the disease pathogenesis. Electron microscopy showed that CD14+ monocytes/macrophages from patients with acute KD had nuclei with complex shapes, apparent nucleoli and abundant intracytoplasmic granules, some of which were positive for acid phosphatase. The quantity of intracytoplasmic granules was correlated with disease severity, in terms of the duration of fever, maximum level of C-reactive protein and the presence of coronary artery lesions (CAL), suggesting that the monocytes/macrophages were activated and showed increased phagocytosis. Immunocytochemical staining of smears made from cell suspensions of sorted CD14+ monocytes/macrophages was carried out using a monoclonal antibody against tumor necrosis factor (TNF)-alpha. The cytoplasm of monocytes/macrophages from patients with acute KD was strongly positive in comparison to that of cells from control subjects, suggesting that intracytoplasmic granules secrete TNF-alpha.