The Clinical Significance of IgG Antibodies to Native Human Type II Collagen in Patients with Rheumatoid Arthritis

Kim, Ho Youn; Lee, Sang Heon; Kim, Wan Uk; Kim, Sung Il; Yoo, Wan Hee; Youn, Jee Hee; Lee, Suk Kyeong; Joo, Young Shil; Park, Jae Ho; Lee, Shin Seok; Min, Jun Ki; Hong, Yeon Sik; Park, Sung Hwan; Cho, Chul Soo

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) (p<0.05). The incidence of anti-HnCII positivity was also higher in RA than OA (39.1% vs. 17.6%) (p<0.05). In 218 evaluable patients, 98 patients with anti-HnCII positive had higher levels of ESR (p<0.001) and CRP (p<0.001) than 120 patients with anti-HnCII negative. The titers of anti-HnCII was also closely correlated with CRP (r=0.385) and ESR (r=0.235). However, no differences were found in titers of rheurnatoid factor, positivity of rheumatoid factor and hemogiobin levels. Incidence of anti-HnCII positivity was not related to disease duration (31/59 in <3 year, 63/148 in >3 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.