Association of anti-RNP with HLADR4 and its prevalence in rheumatoid arthritis patients.

Background: Autoantibodies are useful diagnostic tools for a variety of rheumatic autoimmune disorders.

Objective: The aim of the present study was to investigate autoantibodies against the 70-kD polypeptide of U1 ribonucleoprotein antibodies (RNP) in patients with rheumatoid arthritis (RA) and to investigate the relationship between anti-RNP and HLARD4 in RA patients.

Patients And Methods: In this prospective study, we studied 80 RA patients. The patients were classified according to 2010 ACR/EULAR Rheumatoid Arthritis Classification Criteria. The patients were 66 females and 14 males. Patients were classified according to activity, duration of disease, and rheumatoid factor. Thirty healthy individuals were included in the study as a control group. Anti-RNP were determined by enzyme-linked immunosorbent assay and HLADR4 was investigated by gel electrophoresis polymerase chain reaction.

Results: Anti-RNP were positive in 32 patients from 80 patients and negative in all control patients. HLADR4 was positive in 53 RA patients from 80 patients and was positive in 6 controls from 30 controls. There was a positive correlation between HLADR4 and anti-RNP (r = 0.368) (P < 0.01). Anti-RNP levels in rheumatoid patients were higher than anti-RNP levels in control patients. Also, there was a positive correlation between anti-RNP and HLADR4 in rheumatoid patients.