FCGR2B and systemic lupus erythematosus: To study how IgG Fc glycosylation is associated with the development of autoimmune pathology, we first used lupus-prone FcγRIIB knockout mice, a model of spontaneous lupus nephritis (Fcgr2b−/− females on the C57BL/6, haplotype b, background) (46, 48–50).