Development and validation of an enzyme-linked immunosorbent assay for feline trypsin-like immunoreactivity

Objective—To develop and validate an ELISA for quantitative analysis of feline trypsin-like immunoreactivity (fTLI). Sample Population—Purified feline cationic trypsin (fCT) and rabbit anti-fCT antiserum; blood samples from 63 healthy cats. Procedures—A sandwich capture ELISA was developed, using anti-fCT antiserum purified by affinity chromatography that underwent biotinylation. Purified fCT was used for standards. The assay was validated by determination of sensitivity, working range, linearity, accuracy, precision, and reproducibility. A reference range was established by assaying serum samples from the 63 healthy cats. Results—Sensitivity was 1.23 µg/L; working range was 2 to 567 µg/L. Ratios of observed versus expected results for 4 samples tested at various dilutions ranged from 90.0 to 120.7%. Ratios of observed versus expected results for 5 samples spiked with various concentrations of fCT ranged from 82.0 to 101.8%. Intra- and inter-assay coefficients of variability ranged from 9.9 to 11.1% and f...