Quantitative studies of monoclonal antibody 5-1-6-induced proteinuric state in rats.
Murine monoclonal antibody (MoAb) 5-1-6 was already reported to bind to epithelial cell foot processes and to cause proteinuria in rats. In vivo kinetics of the injected MoAb 5-1-6, relationship between the quantity of kidney-binding antibody and proteinuria, and changes in the amount of antigenic molecule recognized by this MoAb in the proteinuric state were studied. The amount of total kidney-binding antibody (TKAb) as determined 1 h after a 2 mg administration was 50.8 +/- 10.4 micrograms/2 kidneys, and TKAb declined to 1.9 +/- 0.4 at day 15. The minimum dose of MoAb required to induce proteinuria was 125 micrograms as the injected dose. This dose corresponded to 12.8 micrograms of TKAb at 1 h and 0.34 micrograms of TKAb at day 5. The amount of MoAb 5-1-6 binding to isolated normal glomeruli was also shown to exceed 147.7 micrograms/76,000 glomeruli, indicating proteinuria to be induced provided more than 8.7% (= 12.8/147.7) of the critical epitopes is specifically occupied by MoAb. The total amount of MoAb 5-1-6 bound to glomeruli in vivo and in vitro was assayed with [125I]-labelled anti-mouse IgG. The amount of [125I] anti-mouse IgG bound to glomeruli was 6.93 +/- 0.45 micrograms/10,000 glomeruli from rat 5 days after this MoAb injection and 26.58 +/- 0.66 micrograms/10,000 control glomeruli, indicating the decrease in the number of MoAb 5-1-6-recognized antigen molecules in glomeruli isolated from the rat in proteinuric state induced by this MoAb. Thus, the MoAb 5-1-6-recognized molecule itself may principally function to regulate the permeability of the glomerular capillary wall and the decrease of the molecule may lead to proteinuria.
Kawachi
H
H
Department of Immunology, Niigata University School of Medicine, Japan.
Matsui
K
K
Orikasa
M
M
Morioka
T
T
Oite
T
T
Shimizu
F
F
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D004306:Dose-Response Relationship, Immunologic; D004848:Epithelium / Q000276:immunology; D005260:Female; D007678:Kidney Glomerulus / Q000166:cytology / Q000276:immunology*; D011507:Proteinuria / Q000209:etiology*; D051381:Rats; D011919:Rats, Inbred Strains
D000911:Antibodies, Monoclonal