To evaluate soluble interleukin-2 receptor alpha chain (sIL-2Rα, sCD25) in serum for the determination of rheumatoid arthritis (RA) activity.
Peripheral blood was collected from 108 patients with RA, 39 patients with osteoarthritis (OA) and 50 healthy control subjects, and synovial fluids were from 40 patients with RA. The sera from the patients with RA, the disease control group (osteoarthritis), the healthy control group, and the synovial fluids of the RA patients were detected by enzyme-linked immunosorbent assay (ELISA).The clinical manifestations and laboratory parameters of the patients with RA were recorded and the correlation with the serum sCD25 level was analyzed.
The serum sCD25 concentration in RA group was (2 886±1 333) ng/L, the serum sCD25 concentration in OA group was (2 090±718) ng/L, and the serum sCD25 concentration in healthy group was (1 768±753) ng/L. The serum sCD25 level in the patients with RA was significantly higher than that in the disease controls and healthy controls (P<0.001). Sensitivity of serum sCD25 in the diagnosis of RA was 66.1% and specificity was 83.0%;serum sCD25 levels and erythrocyte sedimentation rate (r=0.321, P=0.001), C-reactive protein (r=0.446, P<0.001), DAS28 score (r=0.324, P<0.001), joint tenderness count (r=0.203, P=0.024), D-dimer levels (r=0.383, P<0.001), age (r=0.24, P=0.007), IgG (r=0.207, P=0.028), HRF-IgG (r=0.345, P=0.034) showed a significant positive correlation, and disease duration (r=-0.206, P=0.021) showed a negative correlation with sCD25;In patients with rheumatoid arthritis, the positive rates of serum ESR, CRP, and sCD25 were 14.3% (2 cases), 14.3% (2 cases), and 71.4% (10 cases) in the low disease activity group. The positive rates of serum ESR, CRP and sCD25 in the moderate disease activity group were 94.2% (49 cases), 82.7% (43 cases), and 86.5% (45 cases). The positive rates of serum ESR, CRP, and sCD25 in the high disease activity group were 100% (42 cases), 95.2% (40 cases), and 90.5% (38 cases);36 cases of ESR and/or CRP were negative (about 33.3%) in 108 patients, serum sCD5 levels of 17 cases in these 36 cases (about 47.2%)increased, of which 14 cases (about 82.4%) had a DAS28 score higher than 3.2.
The serum sCD25 has a high specificity for diagnosis of RA and a poor sensitivity. The serum level is closely related to the activity of RA, indicating that sCD25 may be involved in the inflammatory process of RA and may become a new inflammatory marker of RA. It is more meaningful for detection of serum sCD25 when RA is active, but ESR and/or CRP is negative.