Ultrastructural localization by monoclonal antibodies of brush border antigens expressed by glomeruli. I. Renal distribution.

The authors have previously reported the production of monoclonal anti-brush border antibodies defining two glycoprotein (gp) antigens of 90 and 330 kd which are also expressed on glomerular cells and may thus be of significance for in situ formation of immune complexes. The 330-kd antigen is involved in Heymann's nephritis, whereas the 90-kd antigen induces transient glomerular immune deposits. In this report, the authors describe the renal ultrastructural localization of the two antigens, which are both detectable on brush border and glomerular epithelial cells but assume contrasting patterns: gp 90 is diffusely present on the cell membranes, whereas gp 330 is concentrated in the intermicrovillar region and within the coated pits. Their localization within proximal tubular cells, on the membrane of intracytoplasmic vesicles, suggests that they are involved in endocytosis. In addition, gp 90 is expressed on endothelial cells lining glomerular capillaries. These observations may help us to understand the formation and different kinetics of immune glomerular deposits.