Experimental glomerulonephritis induced in rabbits by horseradish peroxidase. Mesangial uptake and processing of...

Phagocytosis of immune complexes by glomerular mesangial cells was studied in rabbits in which immune complex nephritis was induced with subcutaneously injected horseradish peroxidase (HRP). Polymorphonuclear leukocytes accumulated in the glomerular capillary lumina, and the mesangial matrix increased soon after the last injection of HRP. The HRP-anti-HRP immune complexes localized diffusely in the mesangial matrix, and some of the complexes were phagocytosed by mesangial cells. After 7 days, the complexes localized to the vascular pole of the glomerulus, but they could not be detected as electron-dense deposits by electron microscopy. These studies indicate the involvement of mesangial cells in phagocytosis and elimination of immune complexes in rabbits with HRP-anti-HRP immune complex nephritis.