In this study we analyze the ability of
antibodies that produce passive Heymann
glomerulonephritis to induce
antigen redistribution on the surface of cultured glomerular visceral epithelial cells (GEC). Polyclonal
antibodies produced by immunization with membrane vesicles prepared from proximal tubule brush borders (BB) and polyclonal (rabbit) and monoclonal (mouse)
antibodies to a
membrane glycoprotein (gp 330) purified from epithelial cells of rat proximal tubule were used. The study by immunofluorescence of GEC kept at 4 degrees C or fixed with
paraformaldehyde showed that the three antibody preparations reacted with the plasma membrane in a punctate pattern known to be due to staining of coated pits or coated vesicles on the cell surface. At 37 degrees C and, at a slower rate, at 22 degrees C, the two polyclonal
antibodies induced a rapid clustering of
antigen-antibody complexes on the nonadherent surface of living cultured GEC with subsequent formation of patches and caps and, after prolonged incubation, with temporary disappearance of
Heymann antigen from the cell surface, so-called antigenic modulation.
Antigen redistribution and modulation were inhibited by
sodium azide, indicating that these processes are energy dependent. Monovalent
Fab fragments of
antibodies to BB vesicles did not alter the distribution of
Heymann antigen unless they were subsequently cross-linked. Monoclonal anti-gp330 induced a modest degree of
antigen redistribution, which was increased by subsequent cross-linking. Exposure of glomerular epithelial cells to
cytochalasin B,
colchicine, or
ionophore A23187 prevented or altered
antigen redistribution at 37 degrees C. Furthermore, the antibody-induced
antigen redistribution was associated with changes in distribution of cytoplasmic actin,
myosin, and
tubulin, indicating that it is related to the contractile activity GEC. LEW rats, given i.v. injection of
IgG directed against BB membrane vesicles, developed passive Heymann
glomerulonephritis (i.e., immune deposits in the lamina rara externa of the glomerular basement membrane). In contrast, the glomeruli of rats exposed for longer periods to larger amounts of
Fab fragments of the same
antibodies failed to develop immune deposits. These studies show that the
antibodies to the
nephritogenic antigen of Heymann
glomerulonephritis may induce a redistribution of
immune complexes (IC) in the membrane of glomerular epithelial cells that is similar to that produced by other plasma membrane
antigen-
ligand interactions.(ABSTRACT TRUNCATED AT 400 WORDS)