Fluorescence immunoassay method using an antigen-binding protein comprising a polypeptide comprising a fluorescently-labeled antibody variable region

摘要

Provided are an antigen measurement or detection kit whereby it is possible to measure an antigen concentration using as an indicator thereof a negative correlation between the fluorescence intensity of a fluorescent dye and an antigen concentration, and an antigen measurement or detection method which uses the kit. An antigen concentration measurement or detection kit including an antigen-binding protein comprising a polypeptide including an antibody light chain variable domain and a polypeptide including an antibody heavy chain variable domain, any one or both of the polypeptide including an antibody light chain variable domain and the polypeptide including an antibody heavy chain variable domain being labeled by a fluorescent dye, the antigen concentration measurement or detection kit characterized in that when the antigen-binding protein bonds with the antigen to be tested and forms a complex, the complex of the antigen and the antigen-binding protein becomes a quencher of the fluorescent dye, the antigen concentration in the liquid phase and the fluorescence intensity of the fluorescent dye are negatively correlated, and the fluorescent dye is more strongly quenched when the complex of the antigen and the antigen-binding protein is formed, whereby the fluorescence intensity is reduced and it is possible to measure the antigen concentration or visualize the antigen on the basis of measured or detected fluorescence, using as an indicator thereof the negative correlation between the antigen concentration in the liquid phase and the fluorescence intensity of the fluorescent dye.