Development and analytic validation of a sandwich ELISA for the measurement of α1-proteinase inhibitor concentrations in serum and feces of common marmosets (Callithrix jacchus)

OBJECTIVE To develop and validate a sandwich ELISA for the measurement of alpha(1)-proteinase inhibitor (alpha(1)-PI) concentrations in serum and fecal samples obtained from common marmosets (Callithrix jacchus). SAMPLE Leftover serum (n = 42) and fecal (23) samples submitted for diagnostic testing; paired serum and fecal samples obtained from 30 common marmosets at 2 research colonies. PROCEDURES A sandwich ELISA was developed and analytically validated by determining the lower limit of detection, linearity, accuracy, precision, and reproducibility. Reference intervals for alpha(1)-PI concentrations in serum and feces of common marmosets were calculated. RESULTS The standard curve was generated for concentrations between 1 and 100 ng/mL. Mean +/- SD observed-to-expected ratio for serial dilutions of serum and fecal samples was 117.1 +/- 5.6% (range, 112.2% to 123.0%) and 106.1 +/- 19.7% (range, 82.6% to 130.2%), respectively. Mean observed-to-expected ratio for spiking recovery of serum and fecal samples was 102.9 +/- 12.1% (range, 86.8% to 115.8%) and 97.9 +/- 19.0% (range, 83.0% to 125.1%), respectively. Reference interval for serum concentrations of alpha(1)-PI was 1,254 to 1,813 mu g/mL, for 3-day mean fecal concentrations was 11.5 to 42.2 mu g/g of feces, and for 3-day maximum fecal concentrations was 13.2 to 51.2 mu g/g of feces. CONCLUSIONS AND CLINICAL RELEVANCE The ELISA was linear, accurate, precise, and reproducible for quantification of alpha(1)-PI concentrations in serum and feces of common marmosets. However, the ELISA had limited linearity and accuracy for spiking recovery of fecal samples.