The role of apoptotic cell death and bcl-2 protein expression in dermatomyositis

Dermatomyositis isa lymphocyte-mediated disease of autoimmune origin which usually presents in a chronic form. The precise mechanism of muscle cell damage and the fate of lymphocytes during the natural course of the disease are not known. The present study is aimed at investigating whether apoptotic cell death of lymphocytes and muscle fibers is involved in both processes. Eighteen, paraffin-embedded tissue samples from 9 patients were analyzed for morphological signs of apoptotic cell death. Molecular biological detection of DNA fragmentation was examined by the in situ tailing technique. Lesions examined presented different stages of inflammation. There was no indication of cellular apoptosis in the lesions according to morphological criteria for the detection of DNA fragmentation with the in situ tailing reaction. The apoptosis-protective, proto-oncogene protein bcl-2 was detected immunohistochemically and was found to be enriched in the infiltrating T cells. The present study suggests that the absence of apoptotic cell death in dermatomyositis may explain the chronic, progressive course of this autoimmune disease.