We show that a SNP in human FCGR2B that abrogates receptor function is strongly associated with susceptibility to SLE in both Caucasians and Southeast Asians.
FcγRIIb-I232T is a hypofunctional polymorphism associated with lupus susceptibility in humans, an autoimmune disease linked to diminished deletion of autoreactive B cells.
To examine the possibility that another susceptibility gene of primary significance exists within the FcgammaR region, we screened for polymorphisms of the human FCGR2B gene, and examined whether these polymorphisms are associated with SLE.
In the presence of the Yaa lupus-susceptibility locus, FcγRIIB(B6)(-/-) mice do develop lethal lupus, confirming that FcγRIIB deficiency only amplifies spontaneous autoimmunity determined by other loci.
CD19<sup>Cre</sup><i>Yaa</i> mice developed milder lupus than B6.FcγRIIb<sup>-/-</sup><i>Yaa</i> mice, indicating that FcγRIIb deficiency on B cells is not sufficient for the development of severe disease.
To determine whether 7 candidate genes, including tumor necrosis factor receptor II, bcl-2, CTLA-4, interleukin-10 (IL-10), CD19, Fcy receptor type IIA (CD32), and IL-1 receptor antagonist, may contribute to susceptibility to systemic lupus erythematosus (SLE) in the Italian population.
Selective silencing of double-stranded DNA-specific B cells in animals with spontaneous lupus has been achieved previously by the administration of a chimeric antibody molecule that cross-links their DNA-reactive B cell immunoglobulin receptors with inhibitory FcγIIb (CD32) receptors.
Given that the murine lupus susceptibility locus Nba2 includes the IFN-regulated genes Ifi202 (encoding for the p202 protein), Aim2 (encoding for the Aim2 protein), and Fcgr2b (encoding for the FcγRIIB receptor), we investigated whether the IRF5/Blimp-1 axis could regulate the expression of these genes.
Thus CN of FCGR3B, which controls IC responses and uptake by neutrophils, and variations in FCGR2B, which controls factors such as antibody production and macrophage activation, are important in SLE pathogenesis.
Mice that are prone to SLE because of a deficiency in FcγRIIB or overexpression of Toll-like receptor 7 are protected from death caused by cerebral malaria.
We show that a SNP in human FCGR2B that abrogates receptor function is strongly associated with susceptibility to SLE in both Caucasians and Southeast Asians.
Using the two Asian cohorts, significant association of FCGR2B-232Thr/Thr with SLE was observed only in the presence of CD72-*1/*1 genotype (OR 4.63, 95% CI 1.47-14.6, P=0.009 versus FCGR2B-232Ile/Ile plus CD72-*2/*2).
We have identified a polymorphism FCGR2B c.695T>C that results in the non-conservative replacement of 232Ile at the transmembrane helix to Thr and demonstrated the association of the polymorphism with susceptibility to systemic lupus erythematosus (SLE) in Asians.