[Development of an immunoenzyme method for the quantitative determination of an acid-stable trypsin inhibitor in urine: use for assessing the severity of glomerulonephritis].

Acid-stable trypsin inhibitor was isolated from urine of healthy persons; its homogeneous preparation was obtained using absorption on chitosan, affinity chromatography on chymotrypsin-Sepharose 4B and gel filtration of Sephadex G-100. Two forms of the inhibitor were produced with Mr = 44,000 and 22,000; yield of the trypsin inhibitor was about 70% of its content in urine. Indirect immunoenzymatic assay was developed for the inhibitor estimation; optimal conditions were chosen for sorption of the inhibitor on polystyrene plates as well as for dilution of rabbit anti-inhibitor blood serum and of goat antibodies to rabbit antibodies and horse radish peroxidase conjugates. The procedure developed was sensitive; 10-20 ng of the inhibitor was detected per a sample. Urine of healthy persons and of patients with latent and nephrotic forms of glomerulonephritis was studied using the test system developed. The results of estimation of the trypsin inhibitor were considered in diagnostics and evaluation of severity of glomerulonephritis.