Adenosine deaminase binding protein, a new diagnostic marker for kidney disease.

This enzyme immunoassay detects adenosine deaminase binding protein (ABP), a glycoprotein that is shed from the brush border of the proximal tubule in kidney damage. Two monoclonal antibodies, URO-4 and URO-4a, each react with different epitopes on ABP and are used as the "sandwich" pair of antibodies. A linear standard curve can be generated by using partly purified ABP isolated from the urine of patients with kidney disease. Release of ABP into the urine appears to reflect the severity of the insult to the nephron. Therefore, measurement of ABP in urine may help distinguish between tubular disease and glomerular disease and indicate renal allograft rejection in renal-transplant patients.