Difference of IFI44L methylation and serum IFN-a1 level among patients with discoid and systemic lupus erythematosus and healthy individuals

Lupus erythematosus (LE) is an autoimmune disease that can be divided into two types. The cutaneous lupus erythematosus (CLE), such as discoid LE (DLE), affects only the skin. While the systemic lupus erythematosus (SLE) affects the hematopoietic, renal, and other systems. We previously found that IFI44L methylation could be a biomarker for SLE. Here, we detect the IFI44L methylation by high-resolution melting-quantitative polymerase chain reaction (HRM-qPCR) assay. The positive percentages of SLE, DLE and healthy controls (HC) are 96.00%, 27.45%, 2.00%, if the curve of 25% methylation was used as the threshold of SLE. And we determined the serum IFN-a1 level by enzyme-linked immunosorbent assay (ELISA) in SLE, DLE and HC. The serum concentration of IFN-a1 in patients with SLE was significantly higher than in the DLE (12.63 +/- 6.38 pg/mL vs 7.99 +/- 2.28 pg/mL, P < 0.05) and HC (12.63 +/- 6.38 pg/mL vs 7.17 +/- 1.86 pg/mL, P < 0.05). But the expression level of IFN-a1 in serum was not significantly different between DLE and HC (7.99 +/- 2.28 pg/mL vs 7.17 +/- 1.86 pg/mL, P = 0.5365). This suggests that methylation of IFI44L and serum concentration of IFN-a1 may be used as biomarkers to distinguish DLE from SLE.