STUDY OF HUMAN URINARY TRYPSIN INHIBITOR

II. Foundamental and Clinical Investigation of Radioimmunoassay of Human Urinary Trypsin Inhibitor

Abstract

Using a purified human urinary trypsin inhibitor (UTI) and a monospecific anti-UTI antibody, the uthor developed a highly specific and sensitive radioimmunoassay (RIA) for measuring human UTI.
1. The UTI was iodinated by the lactoperoxidase method without loss of the antigenicity of UTI. The sensitivity of this system was from 25 to 200ng and 5 to 50μl of urine was usually used to determine the concentration of UTI.
2. The precision of within-assay, between-assay and the recovery rate obtained were satisfactory. The urine sample was stable over one month at -70°C.
3. When concentrated fresh urine of healthy man was applied to a column of Sephacryl S-200, the fractions containing UTI activity measured by RIA and enzymic assay appeared in a single peak corresponding to bovine serum albumin (M. W. 67, 000).
4. A significant positive correlation between UTI levels of RIA and UTI levels of enzymic assay in healthy humans was confirmed. In healthy humans, UTI levels of RIA and enzymic assay were not correlated with urinary protein, urinary creatinine and urine volume.
5. The UTI levels in men an women were 5.488±4.141 (mean±SD) mg/day and 3.859±1.350mg/day, respectively. In normal subjects, UTI increased during the day time and decreased at night. Its levels in men were higher than in women throughout a day.
6. The UTI excretion in pregnant women was significantly higher than in normal women. Its values were increased as the week of pregnacy progressed.
These results confirmed that RIA of UTI was very useful as a quantitative method.