Type I IFNs increase the production of B lymphocyte stimulator (BLyS) and a proliferation-inducing ligand (APRIL), which are involved in the survival of autoreactive B cells, by mDCs, and this contributes to B cell differentiation and Ig class switching, which are important for generating pathogenic autoantibodies in SLE [7,58,59]. This evidence concerns the gene TNFSF13B and systemic lupus erythematosus.