van den Hoogen LL, et al. - Authors sought to find an easy-to-measure biomarker for the interferon (IFN) signature, which is related to disease activity and is a potential therapeutic target. For detecting the IFN signature in patients with systemic autoimmune diseases such as systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS), galectin-9 is a novel, easy to measure, and therefore, clinically applicable biomarker. In patients with SLE, SLE+APS and primary APS (PAPS), galectin-9, CXCL-10 and tumor necrosis factor receptor type II (TNF-RII) were elevated, and these correlated with disease activity and tissue factor expression. Findings suggested a stronger association of galectin-9 vs CXCL-10 or TNF-RII with the IFN score and was superior to CXCL-10 or TNF-RII in detecting the IFN signature.