Targeted Deletion of <i>fgl2</i> Leads to Impaired Regulatory T Cell Activity and Development of Autoimmune Glomerulonephritis

Abstract Mice with targeted deletion of fibrinogen-like protein 2 (fgl2) spontaneously developed autoimmune glomerulonephritis with increasing age, as did wild-type recipients reconstituted with fgl2−/− bone marrow. These data implicate FGL2 as an important immunoregulatory molecule and led us to identify the underlying mechanisms. Deficiency of FGL2, produced by CD4+CD25+ regulatory T cells (Treg), resulted in increased T cell proliferation to lectins and alloantigens, Th 1 polarization, and increased numbers of Ab-producing B cells following immunization with T-independent Ags. Dendritic cells were more abundant in fgl2−/− mice and had increased expression of CD80 and MHCII following LPS stimulation. Treg cells were also more abundant in fgl2−/− mice, but their suppressive activity was significantly impaired. Ab to FGL2 completely inhibited Treg cell activity in vitro. FGL2 inhibited dendritic cell maturation and induced apoptosis of B cells through binding to the low-affinity FcγRIIB receptor. Collectively, these data suggest that FGL2 contributes to Treg cell activity and inhibits the development of autoimmune disease.

Targeted Deletion of fgl2 Leads to Impaired Regulatory T Cell Activity and Development of Autoimmune Glomerulonephritis Journal Articles