Infiltrating cell profiles of sarcoid lesions in the muscles and peripheral nerves: an immunohistological study

In order to study the pathological mechanisms of neuromuscular sarcoidosis, we carried out an immunohistochemical investigation in five cases (five muscle specimens and two sural nerve specimens). We evaluated the distribution of inflammatory mononuclear cells and major histocompatibility complex (MHC) antigen expressions. Our data showed a dominant infiltration of helper/inducer T cells (CD4-T cells), suggesting the importance of cell-mediated immune responses in neuromuscular sarcoidosis. However, we could not identify the distinct distributional patterns of T cells as reported in sarcoid lymphadenitis. This result may be attributed to the difference of the affected organs. Moreover, failure to detect class II antigens in the muscle fibers may imply the difference in pathogenic mechanism between neuromuscular sarcoidosis and other inflammatory myopathies.