Background Rheumatoid arthritis (RA) is a systemic autoimmune disease with a heterogeneous clinical spectrum. Because of its molecular complexity, to date, validated biomarkers of severity such as rheumatoid factor or anti-citrullinated peptide antibodies are not capable to identify those patients who require more intensive treatment¹, indicating that finding new biomarker for diagnosis of AR is necessary. CD93 is a glycoprotein which is expressed on the cell surface of many immune cells including hematopoietic stem cells², monocytes, platelets³. Recent studies have shown that CD93 is shed from the cell surface of monocytes and forms soluble(s)CD93 during inflammation⁴. sCD93 is enhanced in the serum of patients with systemic sclerosis and correlates with the severity and activity of skin sclerosis. However, the level of this new inflammatory biomarker in patients with RA has not yet been explored.

Objectives The objectives of this research were to determine the levels of sCD93 in serum of patients with RA in comparison with normal individuals

Methods 34 patients with RA and 35 normal individuals were participated in this study. All the control donors were age- and gender-matched with the patients. Patients were diagnosed at Rheumatology Clinic, Tohid Hospital, Sanandaj, Iran. Serum samples were collected and kept at −80°C until they were analyzed by ELISA.

Results The mean age of the patients and control participants were 43±13 and 41±13, respectively. We observed that the serum levels of sCD93 in patients with RA were elevated compared with normal controls. Next, we analyzed the levels of sCD93 in patients with RA and found that the level of sCD93 is much higher in male than female. However, it was similar in both genders in controls individuals. Furthermore, the levels of sCD93 were much higher in smoking patients than non-smoking.

Conclusions We demonstrate for the first time that sCD93 is higher in patients with RA than normal individuals and that sCD93 could be used as biomarker for diagnosis of RA.

References

1. Avouac J, Gossec L, Dougados M. Diagnostic and predictive value of anti-cyclic citrullinated protein antibodies in rheumatoid arthritis: a systematic literature review. Annals of the rheumatic diseases 2006;65(7):845-51.

2. Jalili A, Marquez-Curtis L, Shirvaikar N, Wysoczynski M, Ratajczak M, Janowska-Wieczorek A. Complement C1q enhances homing-related responses of hematopoietic stem/progenitor cells. Transfusion 2010;50(9):2002-10.

3. Bohlson SS, Silva R, Fonseca MI, Tenner AJ. CD93 is rapidly shed from the surface of human myeloid cells and the soluble form is detected in human plasma. The Journal of Immunology 2005;175(2):1239-47.

4. Yanaba K, Asano Y, Noda S, Akamata K, Aozasa N, Taniguchi T, et al. Augmented production of soluble CD93 in patients with systemic sclerosis and clinical association with severity of skin sclerosis. British Journal of Dermatology 2012;167(3):542-7.

Acknowledgements The authosr thanks to Kurdistan University of Medical Sciences for the financial suports

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.5867