Predominant role of FcγRIII in the induction of accelerated nephrotoxic glomerulonephritis

Background. Nephrotoxic glomerulonephritis is induced by the administration of antibody against the glomerular basement membrane (GBM). We demonstrated previously that Fc receptors for immunoglobulin G (IgG) (FcγR) play crucial roles in the induction of accelerated nephrotoxic glomerulonephritis by using FcRγ-deficient (-/-) mice. Since FcRγ-/- mice lack the cell surface expression of two activating FcγRs, FcγRI and FcγRIII. The present study aims to identify the FcγR responsible for the induction of nephrotoxic glomerulonephritis. Methods. Accelerated anti-GBM glomerulonephritis was induced in FcγRI-/-, FcγRIII-/-, and FcRγ-/- mice by preimmunization with rabbit IgG followed by inoculation of rabbit anti-GBM antibody. Histologic analysis and immunostaining of renal sections were performed. Results. FcγRI-/- mice as well as wild-type mice showed severe glomerulonephritis with hypernitremia by the administration of anti-GBM antibody. In contrast, FcγRIII-/- mice showed much milder renal involvement, similar to FcRγ-/-mice. Histologically, FcγRI-/- mice showed intracapillary proliferation, glomerular thrombosis, and crescent formation, whereas FcγRIII-/- mice showed only glomerular hypercellular changes. The depositions of anti-GBM antibodies, autologous antibodies and complement C3 along the GBM were equally observed among all three FcR-/- mouse types by immunostaining. Conclusions. Accelerated nephrotoxic glomerulonephritis is induced predominantly through FcγRIII but not FcγRI.