ABSTRACT
OBJECTIVE: To determine the clinical significance of IgG antibodies to native type II collagen (IgG nCII) in patients with rheumatoid arthritis (RA). METHODS: IgG antibodies to native type II collagen (anti-HnCII) were measured in 287 patients with RA, 34 patients with osteoarthritis (OA) and 50 normal controls by improved ELISA using avidin-biotin system and 100% normal goat serum. The clinical and laboratory variables were investigated in patients with RA at the time of sampling. RESULTS: The titers of anti-HnCII were higher in RA than OA and normal control (median value 5.2 in RA, 3.0 in OA, 1.7 a.u in normal) (p3 year). There was no differences in age, sex, erosions on X-ray, mean steroid dose, use of DMARD, extraarticular manifetations such as lung involvement, rheumatoid nodule, Sjogren's syndrome between groups with anti-HnCII positive and negative. However, deformity was more frequently found in anti-HnCII negative (p<0.05). Among the 83 patients measured anti-HnCII serially (mean interval; 15+/-6 month), 11 of 24 patients with anti- HnCII positve (45.8%) were converted to negative and 19 of 59 patients with anti- HnCII negative (32.2%) were converted to positive. The levels of CRP decreased in groups converted from positive to negative (p<0.05) and vice versa (p<0.05). CONCLUSION: These results suggest that the levels of IgG HnCII fluctuate with positive correlation with acute phase reactants and may reflect the inflammatory activity of RA.