TNFSF13B and systemic lupus erythematosus: Circulating IgA plasmablasts are found in individuals with SLE, some of which secrete anti-dsDNA antibodies, and the plasmablasts can be detected in inflamed kidneys.18, 19 BAFF can promote class switching to IgA2,20 including acting synergistically with APRIL,21 and overexpression of BAFF leads to increased levels of commensal flora-specific serum IgA and the development of nephropathy.22