ELISA for urinary trehalase with monoclonal antibodies: A technique for assessment of renal tubular damage

Background: alpha,alpha-Trehalase, located on renal proximal tubules, is a glycoprotein that hydrolyses alpha,alpha-trehalose to two glucose molecules . Urinary trehalase reflects damage to renal proximal tubules, but its acti vity has not been measured routinely because measurement of catalytic activ ity is rather complicated and because conventional assays for enzyme activi ty might not reflect all of the trehalase protein because of enzyme inactiv ation in urinary samples. Methods: We established novel monoclonal antibodies for human trehalase and a sandwich ELISA for quantification of urinary trehalase. We determined th e urinary trehalase protein concentration with this ELISA and trehalase cat alytic activity, and the results of these two methods were compared. Results: The ELISA system was more sensitive than the detection of enzyme a ctivity and could detect a subtle difference in the amount of trehalase pre sent in renal diseases. The within- and between-assay CVs in the ELISA were 6.7-7.6% and 6.2-8.2%, respectively. Highly significant increases in both the quantity and activity were seen in patients with nephrotic syndrome (ac ute phase), Lowe syndrome, and Dent disease. The quantities were 70- to 200 -fold greater, whereas enzyme activities were, at most, 10-fold higher than those of control subjects. In the detection of small amounts of trehalase in patients with chronic glomerulonephritis and renal anomalies, quantities were better than enzyme activities. Conclusions: We have established an ELISA system for quantification of urin ary trehalase that uses novel monoclonal antibodies. Our ELISA system is si mpler and more sensitive than a conventional activity assay and reflects tr ehalase protein. This ELISA can be a useful as a common tool for clinical a ssessment of renal proximal tubular damage. (C) 2000 American Association f or Clinical Chemistry.