Reagent for an immunoassay

Abstract

The present invention relates to (1) A reagent for an immunoassay of a target substance existing in a free form and a bound form in a specimen, comprising a latex 1 which is immobilized with a monoclonal antibody 1 for the target substance, and a latex 2 which has a different mean particle size from the latex 1 and is immobilized with a monoclonal antibody 2 having a different recognition site for the target substance from the antibody 1 , (2) An immunoassay method comprising reacting the target substance with the reagent of (1) and determining an amount of the substance based on the result of an agglutination reaction among the target substance, the latex 1 and the latex 2 , and (3) A reagent kit comprising a reagent of (1) and a reagent containing an agglutination accelerator for an antigen-antibody reaction.

1 - 11 . (canceled)  
   
   
       12 . An immunoassay method for a target substance existing in a free form and a bound form in a specimen, comprising 
 reacting the target substance with a first latex particle [ 1 ] which is immobilized with a first monoclonal antibody [ 1 ] for the target substance, and a second latex particle [ 2 ] which has a different mean particle size from the first latex particle [ 1 ] and is immobilized with a second monoclonal antibody [ 2 ] having a different recognition site for the target substance from the first monoclonal antibody [ 1 ], and    determining an amount of the substance based on the result of an agglutination reaction among the target substance, the first latex particle [ 1 ] and the second latex particle [ 2 ].    
   
   
       13 . The method according to  claim 12 , wherein the result of the agglutination reaction is a change in turbidity.  
   
   
       14 . The method according to  claim 13 , wherein the target substance is prostate-specific antigen.  
   
   
       15 . A method according to  claim 14 , wherein the first latex particle [ 1 ] is one having the mean particle size of 0.05-0.18 μm and the second latex particle [ 2 ] is one having a mean particle size of 0.18-0.5 μm.  
   
   
       16 . The method according to  claim 12 , wherein the reaction of the target substance with the first latex particle [ 1 ] and the second latex particle [ 2 ] is performed in the presence of a polymer having a side chain of the group represented by the general formula [1]:  
     
       
         
         
             
             
         
       
     
     (wherein each of R 1 -R 3  is an alkyl group optionally having a hydrogen atom or a hydroxyl group independently, and R 4  is an alkylene group)  
   
   
       17 . The method according to  claim 16 , wherein the polymer having a side chain of the group represented by the general formula [1] is a polymer having a monomer unit derived from the monomer represented by the general formula [2]:  
     
       
         
         
             
             
         
       
     
     (wherein R 5  is an alkylene group optionally having a substituent and an oxygen atom in the chain, R 6  is a hydrogen atom or a methyl group, X is an oxygen atom or a —NH— group, and R 1 -R 4  are the same as the above).