Relationship between the level of antibodies to the RA-33 antigen and the course of rheumatoid arthritis

Objective: to study the relationship between the serum level of antibodies to the RA-33 antigen and the characteristics of the course of rheumatoid arthritis (RA). Materials and methods. The study included 88 patients with a diagnosis of RA that met the ACR/EULAR criteria, 2010. All observed study participants were women (n=100%), aged from 22 to 81 years (M ± σ, 54.3 ± 12.1 years). Rheumatoid factor was detected in 64 people (72.7%). 59 (67%) study participants were positive for anti-CCP. The duration of RA was 0.5–30 years (M ± σ, 11.2 ± 8.6 years), the degree of activity according to DAS28: 0 degree of activity – 19 (21.6%) patients, 1 degree – 10 (11.6%), 2 degree – 52 (59.1%), 3 degree of activity – 7 (7.7%) patients. Among the observed patients, individuals with III radiological stage of the disease predominated. Statistical processing was performed using the Statistica 12.5 software package for Windows. Results. The level of anti-RA-33 was assessed in a group of RA patients and healthy donors. The level anti-RA-33 was assessed in a group of RA patients and healthy donors. The level normal anti-RA-33 in healthy people, calculated as M±σ, was 10.3±10.2 U/ml (from 0.1 U/ml to 20.5 U/ml). The average level anti-RA-33 in RA patients, calculated as M±σ, was 12.7±31.6 U/ml (from 0 U/ml to 44.3 U/ml). The increase in the level anti-RA-33, compared with donors, is statistically significant (p=0.025) and was observed in 12.5% RA patients. Among 24 patients with RA seronegative by RF, an increase in the level anti-RA-33 was detected in 2 (8.3%) patients, and among 29 patients seronegative by ACCP - also in 2 (6.9%) patients. An increase in the level anti-RA-33 was mainly observed at the initial stages of the disease and with initial radiographic changes. In patients with an increased level anti-RA-33 (more than 20.5 U/ml), pronounced functional disorders were more often detected. Findings. Thus, it can be concluded that antibodies to anti-RA33 can potentially provide additional diagnostic value in RA. Keywords: rheumatoid arthritis, diagnostics of rheumatoid arthritis, antibodies to RA-33, heterogeneous nuclear ribonucleoprotein, HnRPA2B1.