Anti-SmD1 antibodies are associated with renal disorder, seizures, and pulmonary arterial hypertension in Chinese patients with active SLE.

Detection of autoantibodies in systemic lupus erythematosus (SLE) plays an important role in timely diagnosis and earlier treatment of SLE. In this study, we used a SmD1 polypeptide-based ELISA to determine anti-SmD1 antibody in 269 SLE, including100 naïve (had not been treated with steroids or immunosuppressants at study inception) SLE patients and 169 non-naive SLE patients; 233 controls with other rheumatic diseases (RDC) (70 RA, 40 AS, 73SSc, and 50 SS), and 110 healthy controls (HC) group. The positive rate of anti-SmD1 among all SLE patients was 60.97%, higher than that in the RDC group (13.30%, P = 0.000) or the HC group (9.09%, P = 0.000). The positive rate of anti-SmD1 in non-naive SLE patients was higher than that for anti-dsDNA antibodies (44.97%, P = 0.03). Positivity for anti-SmD1 only was found in 14.00% of naive SLE patients and 16.00% of non-naive SLE patients. In naive SLE patients, the serum concentration of anti-SmD1 was lower after treatment than before treatment (P = 0.039). Active SLE patients positive for anti-SmD1 were more likely to have malar rash, rash, nonscarring alopecia, PAH and hypocomplementemia. High positivity for anti-SmD1 only in patients with SLE indicated the importance and necessity of detection of anti-SmD1 in patients with SLE.