Passive immune complex glomerulonephritis in mice: models for various lesions found in human disease. II. Low avidity complexes and diffuse proliferative glomerulonephritis with subepithelial deposits.

Intravenous injections of mice three times a day for 3 days with soluble complexes of 3 mg. of moderately avid rabbit antibody to chicken egg albumin prepared by dissolution of equivalence precipitates in 80 times the equivalence amount of antigen resulted in a combined mesangial and loop localization of immune complexes. With complexes formed from antibody of low avidity, injected four times a day for 3 days, a predominately subepithelial loop deposition of complexes was observed. Complexes formed from moderately avid antibody gave rise to a mainly mesangiopathic glomerulonephritis, whereas low avidity complexes were associated with a diffuse glomerulonephritis. These results, in combination with those of the previous paper, successfully reproduce the basic form of the lesions seen in active immune complex disease by passive means and suggest that antibody avidity is a major determinant of the site of localization of immune complexes and therefore of the morphologic form of the resulting glomerulonephritis. The importance of these observations for our understanding of the pathogenesis of human immune complex disease is considered.