Characterisation of the 1st SSI purified MBL standard

• Published in: Clinica chimica acta 2008-09, Vol.395 (1), p.159-161
• Main Authors: Laursen, Inga, Højrup, Peter, Houen, Gunnar, Christiansen, Michael
• Format: Article
• Language: English
• Subjects: Calibration; Complement; Electrophoresis, Polyacrylamide Gel; ELISA; Fluoroimmunoassay; Humans; Immuno-deficiency; Innate immunity; Mannan-binding lectin; Mannose-Binding Lectin - blood; Mannose-Binding Lectin - isolation & purification; Mannose-Binding Lectin - standards; Molecular Weight; Reference Standards; Sensitivity and Specificity; Temperature; Time Factors
• ISSN: 0009-8981; 1873-3492
• DOI: 10.1016/j.cca.2008.06.006

Mannan-binding lectin (MBL) is of importance in innate immunity. MBL-deficiency, the most common immune defect, is significant in several clinical contexts. The request for MBL diagnostic is increasing, hence we developed a high-purity MBL standard assigned with a traceable value. The standard material was produced from human plasma; and the protein concentration determined by amino acid analysis after a preceding desalting. The standard value was assessed by two series of sub-sample analyses from nine vials by the grand mean: 235.7 µg protein/ml (range 191.1–280.3 µg/ml). The loss during desalting was 7% and the protein content 253.4 µg/ml after correction. After SDS/PAGE the MBL content was estimated by densitometric scanning. The MBL band (non-MBL bands being MASPs) comprised 76%. Therefore, the standard was assigned a value of 192.6 µg MBL/ml (range 156.0–229.2 µg/ml). A calibrated time-resolved immuno-flourescence assay was used for stability evaluation of the MBL standard, after transfer from − 80 °C, showing stability for at least 10 days at 25 °C, 14 days at 5 °C, and 16 weeks at − 20 °C. The 1st SSI purified MBL standard has been produced, and assigned the value 192.6 µg MBL/ml, traceable to an accurate realisation of the unit.