Abstract
The presently described study was undertaken to modify our solid-phase, two-site enzyme immunoassay method (EIA) for human pancreatic secretory trypsin inhibitor (PSTI) to make it more practical for the quantification of the inhibitor in human body fluids. Peroxidase activity fixed on the solid phase was measured spectrophotometrically with 2, 2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) as a coupling reagent. The analytical range of the assay was from 4 to 1, 000ng/ml when a sample volume of 50μl was used, and PSTI levels so measured in serum correlated well with those measured by conventional radioimmunoassay (n=16, r=0.985, intercept +10.35, and slope 1.12). Both the anti-PSTI monoclonal antibody IgG-coated polystyrene beads and the anti-PSTI monoclonal antibody Fab'-linked peroxidase conjugates were found to be stable for at least 4 months at 4°C. Our evaluation of the resulting method revealed that the procedure is acceptable in regard to linearity, recovery, precision, and specificity. In addition to these qualities the EIA method for PSTI introduced here is reliable and rapid enough to be useful for either routine determinations and/or clinical tests.
