Factor IX (aka Christmas Factor) is a single-chain, 415 amino acid glycoprotein zymogen. Factor IX is activated by either Factor XIa or the Factor VIIa complex. Factor IXa converts Factor X to Factor Xa during the intrinsic pathway of the coagulation cascade. Factor IX is used to treat patients with hemophilia B, an X-linked bleeding disorder. The sensitive quantitative measurement of total human Factor IX antigen in plasma samples is easily performed with this 96 well strip format ELISA kit. Factor IX and IXa will be detected by the assay. The concentration of Factor IX in normal human plasma is about 5 ug/ml. The assay measures total human Factor IX in the 0.1-100 ng/ml range. Samples giving human Factor IX levels above 100 ng/m should be diluted in blocking buffer before use. A 1:500 to 1:1,000 dilution for plasma is suggested for best results. Human Factor IX will bind to the capture antibody coated on the microtiter plate. After appropriate washing steps, anti-human Factor IX primary antibody binds to the captured protein. Excess primary antibody is washed away and bound antibody is reacted with the secondary antibody. Following an additional washing step, TMB substrate is used for color development at 450nm. Color development is proportional to the concentration of Factor IX in the samples. A standard calibration curve is prepared using dilutions of purified Factor IX and is measured along with the test samples. All reagents and standards are provided in these ELISA kits.

The Human Factor IX standard provided in this kit is calibrated against the WHO International Standard for Human Plasma Factors II, VII, IX, X (NIBSC Code 09/172).