The clinical significance of antibodies to heterogeneous nuclear ribonucleoprotein K in rheumatoid arthritis

Masko M.V.

Vitebsk state medical university, Vitebsk, Belarus

Objective. The aim of the study was to investigate the levels and incidence of autoantibodies to heterogeneous nuclear ribonucleoprotein K (anti-hnRNP K) in patients with rheumatoid arthritis (RA) and to analyse the relationships of these antibodies with immunological and clinical parameters.

Methods. The study included 196 individuals: 146 patients with RA and 50 healthy controls. The levels and frequencies of autoantibodies (antibodies to hnRNP K, cyclic citrullinated peptides (ACCP), citrullinated vimentin (anti-Sa), rheumatoid factor (RF)) were determined by enzyme immunoassay (ELISA).

Results. RF, ACPA, anti-Sa, and anti-hnRNP K demonstrated a significantly higher incidence in RA patients compared to the control group (72.6% vs. 0%; 71.9% vs. 0%; 69.9% vs. 2.2% and 35.6% vs. 0%; p<=0.0003, respectively).

Patients with positive and negative results for hnRNP K antibodies did not differ significantly in terms of age, gender, duration, and activity of the disease. However, patients with negative results for hnRNP K antibodies had a significantly higher frequency of extra-articular manifestations (22.9% vs. 7.6%; p<0.05). No differences were found in the level and prevalence of ACСP, RF and anti-Sa between seropositive and seronegative anti-hnRNP K patients with RA. Increased levels and incidence of antibodies to hnRNP K were established in early RA compared to the developed disease (33.7 U/ml vs 13.5 U/ml, p=0.02; 73.9% vs 28.4%, p=0.0001, respectively).

Conclusion. Antibodies to hnRNP K can be considered a new type of autoantibodies associated with RA, which have both clinical and pathogenetic significance in the early stages of RA, and can also be observed in a more favorable course of RA that is not accompanied by systemic manifestations of the disease.