Characterisation of the 1st SSI purified MBL standard.
BACKGROUND
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.


RESULTS
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 microg protein/ml (range 191.1-280.3 microg/ml). The loss during desalting was 7% and the protein content 253.4 microg/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 microg MBL/ml (range 156.0-229.2 microg/ml). A calibrated time-resolved immuno-flourescence assay was used for stability evaluation of the MBL standard, after transfer from -80 degrees C, showing stability for at least 10 days at 25 degrees C, 14 days at 5 degrees C, and 16 weeks at -20 degrees C.


CONCLUSIONS
The 1st SSI purified MBL standard has been produced, and assigned the value 192.6 microg MBL/ml, traceable to an accurate realisation of the unit.
Laursen
Inga
I
Statens Serum Institut, Copenhagen, Denmark. inl@ssi.dk
Højrup
Peter
P
Houen
Gunnar
G
Christiansen
Michael
M
D002138:Calibration; D004591:Electrophoresis, Polyacrylamide Gel; D015200:Fluoroimmunoassay; D006801:Humans; D037601:Mannose-Binding Lectin / Q000097:blood / Q000302:isolation & purification* / Q000592:standards*; D008970:Molecular Weight; D012015:Reference Standards; D012680:Sensitivity and Specificity; D013696:Temperature; D013997:Time Factors
D037601:Mannose-Binding Lectin