Degradation in vivo of articular cartilage in rheumatoid arthritis by leucocyte elastase from polymorphonuclear leucocytes.
Using a specific substrate, no leucocyte elastase activity could be detected in 55 synovial fluids, including 29 from patients with rheumatoid arthritis (RA). However, a high percentage of samples contained phagocytic inclusions of elastase, alpha 1-proteinase inhibitor (alpha 1-PI) and alpha 2-macroglobulin (alpha 2-MG) in both the polymorphonuclear (PMN) and mononuclear phagocytes. Immunofluorescence and indirect peroxidase-antiperoxidase staining of articular cartilage (ACA) from 52% of 21 patients with RA and one with juvenile RA (JRA) showed presence of elastase in the superficial layer of microscopically intact but proteoglycan depleted pannus-free ACA. In histologically altered pannus-free RA-ACA superficial elastase deposits were found in 24% of the cases. Adjacent ACA sections contained IgG, C3, alpha 1-PI and rarely alpha 2-MG. RA-ACA below or surrounded by pannus showed close contact with intact and decaying PMN in 62% and 48% of the cases, respectively. ACA specimens from patients with degenerative disease and systemic lupus were negative. These findings strongly suggest that PMN leucocyte elastase is operative in the degradation of RA-ACA and JRA-ACA, and that this activity is largely dependent upon the presence of entrapped immune complexes in such cartilage.
D000328:Adult; D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000473:pathology; D002358:Cartilage, Articular / Q000378:metabolism* / Q000473:pathology; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D009504:Neutrophils / Q000201:enzymology*; D010196:Pancreatic Elastase / Q000097:blood*; D013582:Synovial Fluid / Q000166:cytology / Q000201:enzymology
D010196:Pancreatic Elastase