To detect the anti-citrullinated glucose-6-phosphate isomerase (GPI) 70-88 peptide antibody (anti-C-GPI(70-88) antibody), anti-citrullinated GPI 435-453 peptide antibody (anti-C-GPI(435-453) antibody), anti-GPI 70-88 peptide antibody (anti-GPI(70-88) antibody) and anti-GPI 435-453 peptide antibody(anti-GPI(435-453) antibody) in the serum of rheumatoid arthritis (RA) patients, and examine the diagnostic values of the anti-C-GPI peptide antibodies in RA.
The anti-C-GPI(70-88) antibody, anti-C-GPI(435-453) antibody, anti-GPI(70-88) antibody and anti-GPI(435-453) antibody were detected by enzyme-linked immunosorbent assay (ELISA) in 191 RA patients, 129 other rheumatic diseases and 74 healthy controls. The clinical and laboratory data of the patients with RA were collected, and the values of anti-C-GPI peptide antibodies in the diagnosis of RA and the relationships of anti-C-GPI peptide antibodies with the clinical and laboratory parameters analyzed.
(1) The mean titers of the anti-C-GPI(70-88) antibody and the anti-C-GPI(435-453) antibody in the RA patients (respectively, 68.71  ±  4.20 and 51.78  ±  3.13) were significantly higher than those with other rheumatic diseases and healthy individuals (P <0.05). However, the mean titers of the anti-GPI(70-88) antibody and anti-GPI(435-453) antibody in the RA patients were similar to those with other rheumatic diseases and healthy individuals. (2) The diagnostic sensitivity and specificity of the anti-C-GPI(70-88) antibody for RA were 41.88% and 84.50% respectively; and the diagnostic sensitivity and specificity of the anti-C-GPI(435-453) antibody for RA were 46.05% and 86.05% respectively. The sensitivity of combined detection of the two anti-C-GPI peptide antibodies was 50.79%, and the specificity was 81.40%. (3) The positive rates of the anti-C-GPI(70-88) antibody and the anti-C-GPI(435-453) antibody were 35% and 45% respectively in those patients with negative anti-cyclic citrullinated peptide antibody, anti-keratin antibody, and rheumatoid factor. (4) There was no significant difference in clinical and laboratory indicators between the anti-C-GPI(70-88) antibody or anti-C-GPI(435-453) antibody positive group and negative group.
The anti-C-GPI(70-88) antibody and anti-C-GPI(435-453) antibody can be detected in the serum of RA patients, and C-GPI may be involved in the pathogenesis of RA. There is a certain diagnostic significance for the sera-negative RA.