title: COMP-C3b complexes in rheumatoid arthritis with severe extraarticular manifestations.
abstract: OBJECTIVE
  To investigate biomarker patterns in rheumatoid arthritis (RA) with extraarticular manifestations.
  
  
  METHODS
  Cartilage oligomeric matrix protein (COMP), COMP-C3b, and soluble terminal complement complexes (sTCC) were measured by ELISA.
  
  
  RESULTS
  COMP-C3b levels were higher in patients with RA than in healthy controls and lower in extraarticular RA (ExRA) than in RA controls. In patients with ExRA, sTCC levels were higher than in RA controls, and correlated inversely with serum COMP-C3b levels in the ExRA group.
  
  
  CONCLUSIONS
  Patients with ExRA had lower levels of COMP-C3b. This may be a consequence of complement consumption or a lower potential for COMP from these patients to activate complement.
authors.affiliation: From the Department of Laboratory Medicine, Section of Medical Protein Chemistry, and the Department of Clinical Sciences, Section of Rheumatology, Lund University, Malmö; the Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; the Oslo University Hospital Rikshospitalet, and University of Oslo, Oslo; the Research Laboratory Nordland Hospital, and University of Tromsø, Tromsø, Norway.
authors.forename: Kaisa E
authors.initials: KE
authors.lastname: Happonen
authors.forename: Tore
authors.initials: T
authors.lastname: Saxne
authors.forename: Lennart
authors.initials: L
authors.lastname: Jacobsson
authors.forename: Gunnar
authors.initials: G
authors.lastname: Sturfelt
authors.forename: Johan
authors.initials: J
authors.lastname: Rönnelid
authors.forename: Tom Eirik
authors.initials: TE
authors.lastname: Mollnes
authors.forename: Dick
authors.initials: D
authors.lastname: Heinegård
authors.forename: Carl
authors.initials: C
authors.lastname: Turesson
authors.forename: Anna M
authors.initials: AM
authors.lastname: Blom
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000276:immunology* / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D064236:Cartilage Oligomeric Matrix Protein / Q000097:blood / Q000276:immunology*; D002358:Cartilage, Articular / Q000276:immunology / Q000378:metabolism; D003179:Complement C3b / Q000276:immunology* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D013582:Synovial Fluid / Q000276:immunology / Q000378:metabolism
chemical_list: D015415:Biomarkers; D064236:Cartilage Oligomeric Matrix Protein; D003179:Complement C3b; C577553:TSP5 protein, human
keywords: CARTILAGE OLIGOMERIC MATRIX PROTEIN; COMPLEMENT SYSTEM; EXTRAARTICULAR MANIFESTATIONS; RHEUMATOID ARTHRITIS