Thermostable Kidney Antigen and Its Excretion into Urine

Fractions of bovine and human kidneys obtained by extraction at 100°C followed by ethanol precipitation (BE fractions) were used for immunization of rabbits. Untreated antisera contained many antibodies to bovine or human tissue extracts. Following proper absorption, anti-bovine kidney BE serum detected a kidney-specific antigen in BE preparations of bovine kidney and anti-human kidney BE serum detected a similar antigen in human kidney BE. There was, however, no cross-reaction between these two antigens. The antigens under investigation had an electrophoretic mobility comparable to serum α-globulin. They were demonstrated in separated cortical and medullary portions of kidneys, but were virtually absent from glomeruli isolated by the method of Krakower and Greenspon. Urinary excretion of the kidney-specific thermostable antigen was demonstrated in calves with experimentally induced tubular damage, and in a human patient suffering from acute tubular necrosis.