Measurement of transcobalamin by ELISA

Background: Transcobalamin is essential for the cellular internalization of cobalamin. Methods to quantify the unsaturated protein are available, but few attempts have been made to develop methods to quantify the sum of unsat urated and cobalamin saturated transcobalamin. Methods: gamma-Globulins from two polyclonal rabbit antibodies against reco mbinant human transcobalamin were used as capture and detection antibodies, and recombinant human transcobalamin was used as calibrator in an ELISA de sign. Results: The ELISA is specific for transcobalamin and has a detection limit of <1.6 pmol/L. The imprecision (CV) is 4-6% for mean concentrations of 13 -70 pmol/L. The central 95% interval for serum from healthy blood donors (n = 77) was similar to 600-1500 pmol/L and showed limited variation with age and sex. No correlation was observed between the marker of acute phase rea ction, C-reactive protein, and transcobalamin in plasma. Conclusions: The ELISA measures total transcobalamin in serum and thus can be used for measurement of transcobalamin in patients treated with cobalami n. (C) 2000 American Association for Clinical Chemistry.