AB0324 Distribution and clinical significance of anti-heterogeneous nuclear ribonucleoprotein a2 antibody in connective tissue diseases

Background The anti-heterogeneous nuclear ribonucleoprotein A2 (hnRNP-A2) antibody is specific for rheumatoid arthritis (RA). But, it is also reported that there is no significant difference between RA and systemic lupus erythematosus (SLE) in terms of the antibody. Objectives To investigate the distribution and clinical significance of anti-hnRNP-A2 antibody in connective tissue diseases. Methods Serum anti-hnRNP A2 antibody level was measured by solid-phase enzyme linked immunosorbent assay (ELISA) in 1464 patients with RA, 209 patients with SLE, 204 patients with ankylosing spondylitis (AS), 63 patients with mixed connective tissue disease (MCTD), 133 patients with undifferentiated connective tissue disease (UCTD), 60 patients with Sjogren syndrome (SS), 47 patients with polymyositis/dermatomyositis (PM/DM), and 45 patients with systemic sclerosis (SSc). The positivity rate of anti-hnRNP-A2 antibody was compared among various patient groups, and its correlation to clinical and laboratory parameters and its diagnostic significance were analysed. Results The positivity rate of anti-hnRNP-A2 antibody was 38.0% (556/1464), 36.8% (77/209), 3.9% (8/204), 52.4% (33/63), 17.3% (23/133), 5.0% (3/60), 4.3% (2/47), and 8.9% (4/45) in RA, SLE, AS, MCTD, UCTD, SS, PM/DM and SSc, respectively. The rate differed insignificantly between the RA, SLE and MCTD groups (p>0.05), but was significantly higher than in other disease groups (p 0.05). In RA patients, anti-hnRNP-A2 antibody weakly correlated negatively to anti-Cyclic citrullinated peptide (CCP) antibody (r=-0.135, p 0.05). Conclusions Anti-hnRNP-A2 antibody can be found in various connective tissue diseases, and its positivity rate is relatively high in RA, SLE and MCTD. It is not a RA-specific antibody. In RA, anti-hnRNP-A2 antibody does not coincide with other RA-related serological indicators; hence, it may serve as an adjunctive indicator for RA diagnosis. References [1] Smolen JS, Aletaha D, McInnes IB: Rheumatoid arthritis [J]. Lancet2016;388(10055):2023–2038. [2] Gavrilă BI, Ciofu C, Stoica V. Biomarkers in Rheumatoid Arthritis, what is new? [J]. J Med Life2016;9(2):144–8. [3] Hassfeld W, Steiner G, Hartmunth K, et al. Demonstration of a new antinuclear antibody (anti-RA33) that is highly specific for rheumatoid arthritis [J]. Arthritis Rheum1989,32:1515–1520. [4] 2004;4(4):288–290. [5] Tomoum HY, Mostafa GA, EI-Shahat EM, Autoantibody to heterogeneous nuclear ribonucleoprotein-A2(RA33) in juvenile idiopathic arthritis: clinical sig. Acknowledgements This work was financially supported by the Science and Technology Innovation Plan of Southwest Hospital (No. SWH2016JCZD-06) and the National Natural Science Foundation of China (No. 30973827). Disclosure of Interest None declared