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 fel ine trypsin-like immunoreactivity (fTLI). Sample Population-Purified feline cationic trypsin (fCT) and rabbit anti-fC T 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 se nsitivity, working range, linearity, accuracy, precision, and reproducibili ty. A reference range was established by assaying serum samples from the 63 healthy cats. Results-Sensitivity was 1.23 mu g/L; working range was 2 to 567 mu g/L. Rat ios of observed versus expected results for 4 samples tested at various dil utions ranged from 90.0 to 120.7%, Ratios of observed versus expected resul ts 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 from 10.2 to 21.7%, respectively. The reference range for serum fTLI measured with this ELISA was 12 to 82 mu g/L Conclusions and Clinical Relevance-Results suggest that an ELISA can be use d to measure serum fTLI in cats. The ELISA was sufficiently sensitive, line ar, accurate, precise, and reproducible for clinical use.