Superior performances of Capillary Electrophoresis (CE) vs. HPLC to detect asialo-Transferrin, an important, although often neglected, component of human transferrin (Tf) glycoforms

BACKGROUND Carbohydrate deficient transferrin (CDT) is widely accepted as the most specific biomarker of chronic alcohol abuse. CDT is the collective name of minor glycoforms of Tf including, traditionally, asialo- and disialo-Tf. Asialo-Tf is characterized by low concentrations hampering its detectability. It is expected that IFCC1 will soon recommend the exclusion of asialo-Tf from the computation of CDT to help standardization. However, in our opinion, asialo-Tf could provide precious additional information to confirm, e.g. in a forensic context, an elevated CDT result, merely based on disialo-Tf. On this basis, in view of a re-evaluation of the potential of asialo-Tf as an additional biomarker of alcohol abuse, the purpose of our investigation was to compare the two most popular separative techniques, i.e. CE and HPLC, in their ability to detect asialo-Tf in real serum samples. METHODS Samples: 25 serum samples from subjects undergoing screening for alcohol abuse were analyzed in parallel with CE and HPLC. Analysis: CE and HPLC methods according to ref. 2. Statistics: Data were analyzed by using non-parametric and parametric statistics. RESULTS Correlation between asialo- and disialo-Tf. CE: y = 0.311 x – 0.330, r2 = 0.524 (n=25); HPLC: Scarce number of asialo-Tf detected (n=5) Correlation between CE and HPLC to determine disialo-Tf: y = 1.177 x – 0.158, r2 = 0.970 (n=25) Detection ability for asialo-Tf. CE: 25 out 32 (range detected 0.10 – 3.78); HPLC: 5 out 32 (range detected 0.51 – 1.61) Separation efficiency [N = 5.54 · (tr / w1/2)2].CE: 51,000 pl; HPLC: 4,200 pl CONCLUSIONS Notwithstanding a comparable performance of CE and HPLC in the determination of disialo-Tf, the ability of CE to detect asialo-Tf proved clearly superior. In fact, CE offers a neatly better separation efficiency of Tf glycoforms, providing sharper and more detectable peaks. In addition, the asialo-Tf peak is located in a very flat region of the electropherogram, far from other potentially interfering peaks. The present results strongly support the use of CE in further studies exploring the potential of asialo-Tf as an additional, important biomarker of alcohol abuse. REFERENCES 1 Helander A et al. Clin Chim Acta 2016; 459:19-24. 2 Bortolotti F et al. Clin Chem 2005; 51:2368-71.