| Objective:Polymyositis/Dermatomyositis(PM/DM) is a group of idiopathic inflammatory myopathies of unknown orign, usually with the subacute or chronic development. The clinical manifestation is characterized by muscle weakness and elevation of the serum enzymes. In muscle biopsies there are inflammatory cells infiltration, muscle fiber necrosis accompanying regeneration and connective tissue proliferation. The etiology of the disease may be related to the autoimmune response triggered by infection, specially virus infection. The response may be predominantly cell-mediated or humoral, or a combination of the two. But the etiology and pathogenesis of the disease remain unknown. The study used six immunofluorescence antibodies and detected the expression and distribution of immunoglobulin and complement in the muscles and skins of PM, DM and overlap syndrome(IM+) cases, in order to study the immunopathogenetic mechanism and clinical significance on skeletal muscle and skin lesions in polymyositis and dermatomyositis.Methods:We selected 51 muscle and 17 skin biopsy specimens altogether. The expression and distribution of immunoglobulin IgA,IgG,IgM and complement C3c,C4c,C1q were detected by direct immunofluorescence techniques in skeletal muscle of 30 cases PM/DM and IM+(including 16 polymyositis, 9 dermatomyositis, 5 overlap syndrome). 21 cases were used as controls including 7 muscular dystrophy, 2 motor neuron disease, 2 lipid storage myopathy, 1 thyrotoxic myopathy, 4 alcoholic myopathy, 2 spinal muscular atrophy, 2 congenital myopathy, 1 normal muscle without neuromuscular diseases, they were also detected by direct immunofluorescence techniques using the same immunofluorescence antibodies. In addition, the expression and distribution of immunoglobulin IgA,IgG,IgM and complement C3c,C4c,C1q were also detected by the same techniques in skin of 17 cases PM/DM and IM+(including 11 polymyositis, 4 dermatomyositis, 2 overlap syndrome).Results: Immunoglobulin IgA,IgG,IgM and complement C3c,C4c,C1q positive rates in skeletal muscle of PM were 75%,62.5%,56.3%,31.3%,25%,25%;immunoglobulin IgA,IgG, IgM and complement C3c,C4c,C1q positive rates in skeletal muscle of DM were 77.8%,77.8%,66.7%,66.7%,33.3%,44.4%; immunoglobulin IgA,IgG,IgM and complement C3c,C4c,C1q positive rates in skeletal muscle of IM+ were 60%,100%,80%,40%,20%,40%. Statistically significant more IgA,IgG,IgM were deposited in PM compared with control(P less than 0.05); statistically significant more IgA,IgG,IgM ,C3c, C4c,C1q were deposited in DM compared with control(P less than 0.05);and statistically significant more IgG,IgM ,C1q were deposited in IM+ compared with control(P less than 0.05). The immune complex positive rates of blood vessel wall were 50% in PM and 66.7% in DM and 40% in IM+; the immune complex positive rates of sarcolemma were 50% in PM and 55.6% in DM and 60% in IM+; the immune complex positive rates of sarcoplasm were 12.5% in PM and 11.1% in DM and 20% in IM+ ; but inflammatory cell staining were not found in skeletal muscle from any case with polymyositis /dermatomyositis and overlap syndrome, and not in the control groups. There is statistically significant difference in the distribution of immune complex in blood vessel wall and sarcolemma in skeletal muscle between PM and control groups(P less than 0.05);there is statistically significant difference in the distribution of immune complex in blood vessel wall in skeletal muscle between DM and control groups(P less than 0.05).In 17 skin biopsy specimens we observed that immunoglobulin IgA,IgG,IgM and complement C3c,C4c,C1q were deposited at the dermoepidermal junction, especially IgG and IgM, in addition, immunoglobulin IgM were deposited in blood vessel wall of the skin.Conclusions: 1. Humoral immunity may play an important role in PM/DM pathogensis, the muscle fibre and skin damage may be related to immunoglobulin/complement deposition and complement activation.2. We will fell simple and direct, fast and hypersensitive, when we use the direct im... |
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