Measurement of Transcobalamin by ELISA

Abstract

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 unsaturated and cobalamin saturated transcobalamin. Methods: γ-Globulins from two polyclonal rabbit antibodies against recombinant human transcobalamin were used as capture and detection antibodies, and recombinant human transcobalamin was used as calibrator in an ELISA design. 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 ∼600-1500 pmol/L and showed limited variation with age and sex. No correlation was observed between the marker of acute phase reaction, 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 cobalamin.

Early changes in vitamin B12 uptake and biomarker status following Roux-en-Y gastric bypass and sleeve gastrectomy

“…Our data challenge the value of judging an early B12 status by total B12 measurements in these patients and also challenge whether B12 status remains normal up to 6 month after surgery. Total B12 roughly represents 20% B12 bound to TC (holoTC) and 80% bound to haptocorrin [14,19]. Only B12 bound to TC is available for the tissues, and is thus called 'active B12'.…”

“…Plasma/serum, was collected and stored at À80 C until further analysis of B12 (ADVIA Centaur CP immunoassay System, Siemens Healthcare Diagnostics) and holotranscobalamin (holoTC) (in-house method; CV 7e8%, ref. [13,14]). All B12 and holoTC analyses on samples from the same patient were performed together after the patients had concluded the study.…”

Uptake of cobalamin and markers of cobalamin status: a longitudinal study of healthy pregnant women

“…TotalTC was measured by an in-house sandwich ELISA with a total imprecision of 4%-6% and an intra-assay imprecision of 3% (12). HoloTC was measured by the TC-ELISA after removal of the apoTC with cobalamin-coated beads (13).…”

Vitamin B12 and vitamin B6 supplementation is needed among adults with phenylketonuria (PKU)

“…Serum total transcobalamin (totalTC) and cobalamin saturated transcobalamin (holoTC) were measured by ELISA (Nexo et al 2000(Nexo et al , 2002 employing an automated ELISA analyser (BEP-2000, Dade Behring, Germany), and serum TC saturation was calculated as holoTC/totalTC. Analytical imprecision was 5% for totalTC and 8% for holoTC.…”