IFNG and systemic lupus erythematosus: BLyS is produced in response to both type I IFN (IFN-α) (89), a heritable risk factor in SLE (13), and type II IFN (IFN-γ) (21), a Th1-type cytokine affected by signaling through IL-2Rα (90, 91), the soluble form of which was similarly increased in the current study.