[Immunopathology of skin lesions in Kawasaki disease]

Histopathological findings of skin lesions in Kawasaki disease (KD) have been characterized by extensive edema associated with the dilatation of small vessels in the papillary dermis. Although the inflammation in KD skin lesions was exudative in nature, neutrophil emigration was slight and most of the infiltrates were mononuclear cells. Immunofluorescent studies using skin biopsy specimens from 10 patients with KD aged from six months to eight years and seven months showed that the infiltrating cells in the dermis and epidermis were mainly composed of CD 3+ T cells and Leu M3+ macrophages, but not B cells. In double immunofluorescence staining with combinations of anti HLA-DR, CD4 and CD8 monoclonal antibodies, the infiltrating T cells were mainly CD4+ HLA-DR+ T cells. Leu 23% cell were also positive on these cells, thereby suggesting those to be activated. Studies of skin specimens obtained from the site of BCG vaccinations in patients with KD showed basically similar but more extensive lesions. As a control, the infiltrating cells in the dermis from patients with measles were examined. In contrast to KD, these cells were mainly CD8+ T cells. Together with the findings that the keratinocytes in the epidermis were positive for HLA-DR, the skin lesions in KD appear to be similar to those found in delayed type hypersensitivity. Thus, macrophages and helper T cells may play a crucial role in the pathogenesis of KD.