Interferon pathway activation in systemic lupus erythematosus

The recognition that a multitude of interferon (IFN)-inducible genes are coordinately expressed in peripheral blood cells of patients with systemic lupus erythematosus (SLE) has contributed to considerable interest in the IFN pathway as a therapeutic target in lupus. Together with data that have accumulated over the past four decades implicat-ing IFN-á in SLE, the gene expression data have resulted in emergence of this cytokine pathway as a focal point for understanding mechanisms of autoimmunity and inflamma-tion in systemic autoimmune diseases. Assays that measure IFN-inducible gene expression in patient cells and tissues and plasma assays that quantify IFN-á protein are providing tools for identification of patients with active disease and who may be responsive to inhibition of the innate immune system component of the altered immune response in SLE. In addition, investigations of the mecha-nisms of induction of IFN pathway activation are suggesting clues to the triggers of autoimmunity in SLE.