Evaluation of the Pro- Trac Tacrolimus Monoclonal Whole-Blood Enzyme-Linked Immunosorbent Assay for Monitoring of Tacrolimus Levels in Patients After Kidney, Heart, and Liver Transplantation

Publisher Website
Google Scholar
Abstract
In a prospective study, we evaluated a novel enzyme-linked immunosorbent assay (ELISA) (Pro-Trac) for determining tacrolimus (FK 506) concentrations in whole blood. Results obtained by the ELISA were compared with those obtained either by microparticle enzyme immunoassay (MEIA) or by high-performance liquid chromatography/mass spectrometry (HPLC-MS). The lower limit of quantitation of the ELISA was 0.5 μg/L. The within-series coefficient of variation (CV) was <11%. For spiked blood samples containing different concentrations of tacrolimus, interassay CV was 23.6% at 2.5 μg/L; however, at 15 and 60 μg/L, interassay CV was 44.9 and 50.8%, respectively. In crossover studies including blood samples from patients after liver, heart, or kidney transplantation, ELISA results correlated with those of the HPLC-MS (r = 0.73) as well as with those generated by MEIA (r = 0.82). The ELISA and MEIA showed 52.3 and 56.2% cross-reactivity with 15-O-demethyltacrolimus, respectively, but only 5.0 and 5.4% cross-reactivity with 13-O-demethyltacrolimus. We conclude that if assay precision in the upper range is improved, the Pro- Trac ELISA might be a valuable alternative to the MEIA for therapeutic drug monitoring of tacrolimus.