Clinical Significance of Autoantibodies to Glucose-6-phosphate Isomerase in Serum of Patients with Rheumatoid Arthritis / 대한류마티스학회지

OBJECTIVE: Anti-glucose-6-phosphate isomerase (GPI) antibody (Ab) is known to be arthritogenic in K/BxN mice. Anti-GPI Ab is present in some patients with rheumatoid arthritis (RA), but their clinical manifestations are not clearly elucidated. The purpose of this study was to evaluate whether GPI serves as a specific autoantigen in patients with RA and to investigate the relationship of anti-GPI Ab with clinical parameters of RA. METHODS: Sera were collected from 54 patients with RA, 15 patients with osteoarthritis (OA) and 28 healthy controls. The samples were tested by enzyme-linked immunosorbent assay (ELISA) using human recombinant GPI as antigen. Patients with RA were classified according to rheumatoid factor (RF) positivity, the presence of RA shared epitope (SE), the presence of extraarticular manifestations, and evidence of bony erosive changes. RESULTS: Serum levels of anti-GPI Ab were higher in patients with RA than controls (1599.46+/-1022.48 versus 344.82+/-223.16 AU, p<0.001), and the levels of patients with OA were also higher than controls (1161.47+/-917.44 versus 344.82+/-223.16 AU, p<0.01). In RA, there were no significant difference in anti-GPI Ab levels according to RF positivity, the presence of RA SE, the presence of extraarticular manifestations, and evidence of bony erosive changes. CONCLUSION: Our results suggest that anti-GPI Ab may not be RA specific Ab and not related to the severity of RA.

Clinical Significance of Autoantibodies to Glucose-6-Phosphate Isomerase in Synovial Fluid of Patients with Rheumatoid Arthritis / 대한류마티스학회지

OBJECTIVE: Autoantibody against glucose-6-phosphate isomerase (GPI) has been shown to be present in both the serum and synovial fluid (SF) of patients with rheumatoid arthritis (RA). The purpose of this study was to evaluate whether GPI serves as a specific autoantigen in the SF of patients with RA and to investigate the relationship of anti-GPI antibody with clinical parameters of RA. METHODS: SF was collected from 34 patients with RA and 34 patients with osteoarthritis (OA). The samples were tested by enzyme-linked immunosorbent assay (ELISA) using human recombinant GPI as antigen. Patients with RA were classified according to rheumatoid factor (RF) positivity, the presence of RA shared epitope, the presence of extraarticular manifestations, and evidence of bony erosive changes. RESUTLS: SF levels of anti-GPI antibody were higher in patients with RA than in patients with OA (631.12+/-534.02 AU versus 112.38+/-90.45 AU, p<0.001). In RA, there was no significant difference in SF anti-GPI antibody levels according to RF positivity, the presence of extraarticular manifestations, and evidence of bony erosive changes. CONCLUSION: Autoantibodies to GPI in SF have more related with patients with RA compared with those with OA. In patients with RA, autoantibodies to GPI in SF are not associated with the poor prognostic factors and disease activity of RA.