title: IgG antibodies to type II collagen reflect inflammatory activity in patients with rheumatoid arthritis.
abstract: OBJECTIVE
  To determine the clinical significance of IgG antibodies to type II collagen (CII) and to define any correlation of antibodies to CII with the inflammatory response in patients with rheumatoid arthritis (RA).
  
  
  METHODS
  IgG antibodies to native human type II collagen (IgG anti-CII) were measured in sera and synovial fluid (SF) from patients with RA, patients with osteoarthritis (OA), and healthy controls by an improved ELISA. Demographic, clinical, and laboratory data including tumor necrosis factor-alpha (TNF-alpha) and interleukin 6 (IL-6) levels were also obtained at the time of sampling in patients with RA.
  
  
  RESULTS
  The median level and positivity for circulating IgG anti-CII were higher in patients with RA (n = 297) than patients with OA (n = 34) and healthy controls (n = 50) (p < 0.001). The titers of IgG anti-CII in SF were also higher in RA (n = 45) than in OA (n = 16) (p < 0.001). In paired samples, the levels of IgG anti-CII were significantly higher in SF compared to the sera in patients with RA (n = 45) (p < 0.001), but levels were not different in patients with OA (n = 16). Circulating IgG anti-CII converted from positive to negative in 13 patients (10.7%) and from negative to positive in 18 patients (14.8%) among 122 patients with RA in whom IgG anti-CII were monitored sequentially at a mean interval of 12.2 months. IgG anti-CII positive patients (n = 98) had shorter disease duration (p = 0.04) and less frequent deformity (p = 0.013), and higher median erythrocyte sedimentation rate (ESR) (p = 0.001) and C-reactive protein (CRP) (p < 0.001) than IgG anti-CII negative patients (n = 120). The levels of IgG anti-CII correlated with CRP (r = 0.270) and ESR (r = 0.253). CRP decreased significantly in patients (n = 13) who converted from IgG anti-CII positive to negative (p = 0.013). IgG anti-CII positive patients (n = 40) had higher levels of TNF-alpha and IL-6 than negative patients (n = 40) (p < 0.001). Levels of IgG anti-CII correlated well with TNF-alpha (r = 0.617) and IL-6 (r = 0.347).
  
  
  CONCLUSIONS
  Increased IgG anti-CII in sera and SF in RA correlated directly with acute phase reactants and the proinflammatory cytokines TNF-alpha and IL-6. Our data suggest that IgG anti-CII could reflect inflammatory activity with a potential to destroy cartilage in the early stages of RA.
authors.affiliation: Catholic Research Institutes of Medical Science, Department of Internal Medicine, Kang-Nam St. Mary's Hospital, The Catholic University of Korea, Seoul.
authors.forename: W U
authors.initials: WU
authors.lastname: Kim
authors.forename: W H
authors.initials: WH
authors.lastname: Yoo
authors.forename: W
authors.initials: W
authors.lastname: Park
authors.forename: Y M
authors.initials: YM
authors.lastname: Kang
authors.forename: S I
authors.initials: SI
authors.lastname: Kim
authors.forename: J H
authors.initials: JH
authors.lastname: Park
authors.forename: S S
authors.initials: SS
authors.lastname: Lee
authors.forename: Y S
authors.initials: YS
authors.lastname: Joo
authors.forename: J K
authors.initials: JK
authors.lastname: Min
authors.forename: Y S
authors.initials: YS
authors.lastname: Hong
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: S H
authors.initials: SH
authors.lastname: Park
authors.forename: C S
authors.initials: CS
authors.lastname: Cho
authors.forename: H Y
authors.initials: HY
authors.lastname: Kim
mesh_terms: D000209:Acute-Phase Proteins / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000032:analysis* / Q000097:blood / Q000134:cerebrospinal fluid; D001172:Arthritis, Rheumatoid / Q000276:immunology* / Q000378:metabolism*; D003094:Collagen / Q000276:immunology*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis* / Q000097:blood / Q000134:cerebrospinal fluid; D018836:Inflammation Mediators / Q000378:metabolism; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000276:immunology; D012016:Reference Values; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000209:Acute-Phase Proteins; D000906:Antibodies; D007074:Immunoglobulin G; D018836:Inflammation Mediators; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D003094:Collagen