Charge-related deposition of immune complexes in the glomerular basement membrane is independent of Fc effector function.

Differently charged immune complexes composed of fragments of bovine gamma globulin (BGG) antigen and fragments of rabbit anti-BGG antibody lacking FC portions were used for a study of the role of charge in deposition and localization within the mouse glomerulus. Preformed soluble complexes were made from native heterogeneous, cationic, or anionic F(ab')2 fragments of BGG and of rabbit antibody to BGG, and were injected intravenously. The distribution in the kidney was studied by immunofluorescence and electron microscopy. Cationic but not anionic or heterogeneous complexes diffusely localized in the glomerular basement membrane in both subepithelial and subendothelial sites. In contrast, more neutral or anionic complexes localized less prominently and were limited to the mesangium. The findings suggest that electrostatic interactions independent of Fc effector functions of immunoglobulins can be responsible for glomerular immune complex localization.