Intra and inter-laboratory reproducibility of a monoclonal antibody cocktail based ELISA for detection of allergen specific IgE in dogs: Proficiency monitoring of macELISA in six laboratories

The purpose of this study was to evaluate the reproducibility of results yielded using a monoclonal antibody based ELISA for detection of allergen specific IgE when run in six separate affiliated laboratories. On two separate occasions, duplicate samples of 15 different sera pools were independently evaluated by each laboratory in a single blinded fashion. The average intra-assay variance among reactive assay calibrators in all laboratories was 6.2% (range 2.6-18.2%), while the average intra-laboratory inter-assay variance was 12.1% (range 8.0-17.1%). The overall inter-assay inter-laboratory variance was consistent among laboratories and averaged 15.6% (range 15.1-16.6%). All laboratories yielded similar profiles and magnitudes of responses for replicate unknown samples; dose-response profiles observed in each of the laboratories were indistinguishable. Considering positive/negative results, inter-assay inter-laboratory concordance of results exceeded 95%. Correlation of OD values between and among all laboratories was strong (r>0.9, p<0.001). Correlation of OD values between the two separate evaluations was also high for all allergens except olive, which was attributed to lot-to-lot differences of allergen coated wells. Collectively, the results demonstrated that the monoclonal antibody based ELISA for measuring allergen specific canine IgE is reproducible, and documents that consistency of results can be achieved not only in an individual laboratory, but between laboratories using the same monoclonal-based ELISA.