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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Animals, Antibodies, Monoclonal, Arthritis, Rheumatoid, Fibroblasts, Fibronectins, Humans, Mice, Microscopy, Immunoelectron, Rabbits, Synovial Membrane.
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Is eDA-containing fibronectin synthesized from rheumatoid synovial fibroblast-like cells? Context: To identify the cells that synthesize EDA-containing fibronectin (FN) and examine the role of EDA+FN in the pathogenesis of rheumatoid joint lesions. Localization of EDA+FN and c-Fos protein in rheumatoid joints was studied immunohistochemically by utilizing antibodies for EDA+FN and c-Fos. Expression of EDA+FN was studied by immunoelectron microscopy and in situ hybridization. The amount of EDA+FN was measured by enzyme-linked immunosorbent assay. EDA+FN was specifically localized in the synovial lining layer of synovium with active rheumatoid arthritis (RA) (n = 17), but not in that with osteoarthritis (n = 4) or with inactive fibrous RA (n = 2). EDA+FN messenger RNA was localized in the synovial lining layer. EDA+FN was immunoelectron microscopically localized in the synovial lining fibroblast-like (type B) cells. EDA+FN was also detected at the cartilage-pannus junction and on the surface of RA cartilage. Double staining showed that EDA+FN colocalized with c-Fos protein in the rheumatoid synovial lining layer. Quantification of EDA+FN showed that it was highly concentrated in rheumatoid synovial fluids.
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EDA+FN is synthesized by the synovial lining fibroblast-like (type B) cells in situ in rheumatoid synovium, and appears to be expressed in association with activated or transformed states of synovium. Final Decision: yes