Immunopathology and cytokine detection in the skin lesions of patients with Kawasaki disease.

To investigate the pathogenesis of Kawasaki disease, we examined biopsy specimens from the skin lesions of 10 Japanese patients at the site of the polymorphous exanthem on the hip and at the site of an inoculation with BCG (bacillus Calmette-Gruérin) vaccine of two of them. Ten normal patients were also examined for control purposes. The histopathologic features of the skin lesions were characterized by extensive edema with dilation of the small blood vessels in the papillary dermis; the site of BCG vaccine inoculation showed much greater inflammatory change; neutrophil emigration was weak and most of the infiltrates were CD4+ T lymphocytes and CD13+ macrophages. The expression of the DR locus of human leukocyte antigen was detected not only on the epidermal keratinocyte surface but also on the walls of the small blood vessels and the infiltrating cells around these blood vessels. We also detected cytokines in the skin lesions: (1) interleukin-1 alpha and tumor necrosis factor alpha were strongly positive in all patients with acute Kawasaki disease, (2) interleukin-2 and interferon gamma were weakly or partially positive, (3) no cytokines were detected in the convalescent phase, and (4) the amounts of cytokines at the site of BCG vaccine inoculations were larger than those at the site of the polymorphous exanthem. These findings suggest that CD4+ T lymphocytes and CD13+ macrophages are activated and interleukin-1 alpha and tumor necrosis factor alpha may be involved in the pathogenesis of the inflammation of acute Kawasaki disease.