Psa assay and reagent therefor

Abstract

Provided is a method for the simple and highly accurate assay of PSA by a one-step reaction that does not use carriers having different average grain sizes. Also provided is a reagent therefor. The PSA assay method comprises sensitizing insoluble carriers having the same average grain size within a range of greater than 0.20 μm but 0.40 μm or less using two types of anti-PSA monoclonal antibodies having different epitopes that are anti-PSA monoclonal antibodies that will react with both free PSA and PSA-ACT, which is a complex of free PSA and α1-antichymotrypsin, and bringing the carriers into contact with a sample in the presence of an aggregation promoter.

1 . A PSA assay comprising using insoluble carriers immobilizing thereon two kinds of anti-PSA monoclonal antibodies, and bringing the insoluble carriers into contact with a sample in the presence of an agglutination accelerator, wherein the two kinds of anti-PSA monoclonal antibodies can react with both free PSA and complex of free PSA and α1-antichymotrypsin (PSA-ACT) and recognize different epitopes, and the insoluble carriers have an identical average particle size that is more than 0.20 μm and equal to or less than 0.40 μm. 
     
     
         2 . The PSA assay according to  claim 1 , wherein the agglutination accelerator is one or more agglutination accelerators selected from polyethylene glycol, a polysaccharide, polyvinylpyrrolidone, polyvinyl chloride, a poly-γ-glutamate, and poly(2-methacryloyloxyethylphosphorylcholine). 
     
     
         3 . The PSA assay according to  claim 1 , wherein the insoluble carriers are of one or more type selected from particles comprising materials derived from latex particles of synthetic polymers, silica, alumina, carbon blacks, metal compounds, metals, ceramics, and/or magnetic substances. 
     
     
         4 . The PSA assay according to  claim 1 , wherein the concentration of the agglutination accelerator is adjusted so that an equimolar response to free PSA and complex of free PSA and α1-antichymotrypsin (PSA-ACT) is obtained. 
     
     
         5 . The PSA assay according to  claim 2 , wherein the polysaccharide is one or more polysaccharides selected from dextran, pullulan, and alkylated polysaccharides including methyl cellulose and ethyl cellulose. 
     
     
         6 . The PSA assay according to  claim 3 , wherein the synthetic polymer is one or more synthetic polymers selected from polystyrene, a styrene-sulfonic acid copolymer, a styrene-methacrylic acid copolymer, an acrylonitrile-butadiene-styrene copolymer, a vinyl chloride-acrylate copolymer, and a vinyl acetate-acrylate copolymer. 
     
     
         7 . The PSA assay according to any one of  claims 1  to  6 , wherein the two kinds of anti-PSA monoclonal antibodies have a ratio (fKd/cKd) of a dissociation constant (fKd) for free PSA to a dissociation constant (cKd) for complex of free PSA and α1-antichymotrypsin (PSA-ACT) of more than 0.1 and equal to or less than 2.0, and have a dissociation constant (fKd) for free PSA of 10 nM or less. 
     
     
         8 . A PSA assay reagent comprising at least 1) and 2);
 1) antibody-immobilized carriers prepared by using insoluble carriers immobilizing thereon two kinds of anti-PSA monoclonal antibodies, wherein the two kinds of anti-PSA monoclonal antibodies can react with both free PSA and complex of free PSA and α1-antichymotrypsin (PSA-ACT) and recognize different epitopes, and the insoluble carriers have an identical average particle size that is more than 0.20 μm and equal to or less than 0.40 μm   2) one or more agglutination accelerators selected from polyethylene glycol, a polysaccharide, polyvinylpyrrolidone, polyvinyl chloride, a poly-γ-glutamate, and poly(2-methacryloyloxyethylphosphorylcholine).   
     
     
         9 . The PSA assay according to  claim 1 , wherein the two kinds of anti-PSA monoclonal antibodies have a ratio (fKd/cKd) of a dissociation constant (fKd) for free PSA to a dissociation constant (cKd) for complex of free PSA and α1-antichymotrypsin (PSA-ACT) of more than 0.1 and equal to or less than 2.0 and have a dissociation constant (fKd) for free PSA of 10 nM or less, the agglutination accelerator is one or more agglutination accelerators selected from polyethylene glycol, a polysaccharide, polyvinylpyrrolidone, polyvinyl chloride, a poly-γ-glutamate, and poly(2-methacryloyloxyethylphosphorylcholine), and the amount of the agglutination accelerator is adjusted so that an equimolar response to free PSA and complex of free PSA and α1-antichymotrypsin (PSA-ACT) is obtained.