TLR7 and systemic lupus erythematosus: Although elevated levels of IRF-8 have been shown to play a critical role in TLR7/IFN-α-mediated differentiation of M-MDSCs in a lupus model [36], earlier studies have identified IRF-8 as a negative regulator of MDSC accumulation and the development of suppressive phenotypes in various tumor models and cancer patients [39,40].