The production of monoclonal antibodies against glomerular and other antigens of the human nephron.

During our studies on human kidney tubular antigens we have applied the technique of cell fusion for the preparation of monoclonal antibodies. For this purpose, plasma membranes were prepared from human kidney cortex by homogenization, fractionated on density gradients and selected according to brush border marker enzyme activity. Spleen cells from Balb/c mice hyperimmunized with plasma membranes were fused (PEG) with NS1 plasmocytoma cells by standard procedure. Culture supernatants were tested for presence of specific antibodies by indirect immunofluorescence with fluorescein-conjugated rabbit anti-mouse Fab antibodies on human kidney slices. In two fusions (210 wells), 70 positive hybrids were found secreting antibodies for a variety of antigens in the kidney. Most of them were directed against tubular antigens. In addition, as a by-product, we detected hybridomas which secreted antibodies specific for antigens in other parts of the nephron, such as glomeruli, blood cloning, and monoclonal antibodies were produced in large amounts from ascitic fluid. Some of these antibodies are specific for antigens of the basement membrane, others for antigens of the mesangium. Some recognize antigens present on glomeruli alone, others recognize antigens present on glomeruli and tubules or on glomeruli and blood vessels. We are convinced that the new immunological technique will yield better information on the antigenic microstructure of the nephron. In addition, the monoclonal and, by definition, monospecific antibodies might be useful for diagnostic purposes: recognition and quantitation of the corresponding antigens in the serum and/or urine of patients suffering from kidney diseases.