Independent association of low IFNλ1 gene expression and type I IFN score/IFNλ1 ratio with obstetric manifestations and triple antiphospholipid antibody positivity in primary antiphospholipid syndrome

Recent data suggest an important role of type I interferons (IFN) in antiphospholipid syndrome (APS). Here we aimed to evaluate the interplay of type I and type III (or IFN lambda S) IFNs in APS and potential clinical and serological associations. Our findings suggest that patients with primary APS (PAPS) and systemic lupus erythematosus (SLE)/APS displayed increased type I IFN scores but decreased IFN lambda 1 gene expression levels compared to healthy individuals, as assessed with real-time qPCR analysis in isolated peripheral blood mononuclear cells (PBMCs). Type I IFN score/IFN lambda 1 ratio was remarkably higher in patients with PAPS and SLE/APS as well as in SLE patients with or without antiphospholipid antibodies (aPL) vs controls. In conclusion, our results reveal an association between low IFN lambda 1 expression and obstetric APS. Moreover, the type I IFN score/IFN lambda 1 ratio seems to be a potential marker of high risk APS given its associations with triple aPL positivity.