PT - JOURNAL ARTICLE AU - Sari, Selma AU - Çinar, Suzan AU - Esen, Bahar Artim AU - Gül, Ahmet AU - Öcal, Lale AU - Deniz, Günnur AU - İnanç, Murat TI - P26 Serum BAFF and APRIL as candidate biomarkers in systemic lupus erythematosus (SLE): a prospective follow-up study AID - 10.1136/lupus-2020-eurolupus.74 DP - 2020 Mar 01 TA - Lupus Science & Medicine PG - A40--A41 VI - 7 IP - Suppl 1 4099 - http://lupus.bmj.com/content/7/Suppl_1/A40.3.short 4100 - http://lupus.bmj.com/content/7/Suppl_1/A40.3.full SO - Lupus Sci Med2020 Mar 01; 7 AB - Background BAFF and APRIL are cytokines involved in B cell development and they take place in SLE pathogenesis. The aim of this study was to investigate the relationship between serum BAFF/APRIL levels with clinical features and disease activity in SLE patients.Methods We included 79 patients with SLE (SLICC criteria) and 27 healthy controls into the study. Serum BAFF and APRIL levels were assessed by ELISA. In 19 patients with active disease, BAFF/APRIL levels were reassessed at least 6 months later and disease activity was evaluated by SLEDAI. New renal involvement was observed in 16 patients during the study and renal involvement was previously detected in 12 patients.Results Although both BAFF (median 0.7 vs 0.41 ng/ml) and APRIL (median 2.3 vs 1.05 ng/ml) levels were higher in patients with SLE compared to the control group (p <0.001), no correlation was found between BAFF/APRIL levels and SLEDAI scores. When patients were grouped according to disease activity as no activity (SLEDAI = 0), low disease activity and active disease, there was no difference in BAFF/APRIL levels between groups. Serum BAFF levels were higher in patients with renal disease activity (median 0.94 ng/ml vs 0.61 ng/ml, p=0,01), and there was a positive correlation between APRIL levels and proteinuria (r=0.42, p=0,02). There was no association between BAFF/APRIL levels and anti-dsDNA positivity but a weak inverse correlation was observed between BAFF and C3 levels (r=0.25, P=0.02). No correlation was found between BAFF/APRIL levels and renal SLEDAI scores, histopathologic activity and chronicity index scores. In the active disease group after follow-up, there was no significant changes in BAFF (from 1,63 ng/ml to 1,2 ng/ml) and APRIL levels (from 2,11 ng/ml to 2,31 ng/ml).Conclusions BAFF/APRIL levels were found to be significantly higher in patients with SLE compared to controls, but no association with disease activity was found. BAFF levels are correlated with decreased C3 levels. These results suggest that both cytokines are involved in the pathogenesis of SLE, and that serum BAFF and APRIL levels can be valuable biomarkers in SLE especially in patients with renal activity. Long-term studies on the effect of treatment are needed.Acknowledgements This work was supported by Scientific Research Project Coordination Unit of İstanbul University (Project number: TTU-2016-22314).