Reagent and method for assaying thrombin-antithrombin complex

Abstract

A thrombin-antithrombin complex (TAT) assay reagent is described in which the thrombin-antithrombin complex (TAT) assay reagent includes an antibody bound to a latex particle which binds to the antithrombin part of the complex, and an antibody bound to a latex particle which binds to the thrombin (T) part of the complex. The antibody binding to the antithrombin part of the complex has a reactivity to TAT that is 100 or more times higher than the reactivity to free antithrombin and the assay reagent is preferably designed to achieve a pH of 5.8 to 6.6 during the assay.

1 . A thrombin-antithrombin complex (TAT) assay reagent, the TAT assay reagent comprising:
 an antibody bound to a latex particle which binds to the antithrombin part of the TAT complex and recognizes the complex; and   an antibody bound to a latex particle which binds to the thrombin part of the TAT complex and recognizes the complex;   
       wherein the antibody binding to the antithrombin part of the TAT complex and recognizing the complex has a reactivity to TAT that is 100 or more times higher than the reactivity to free antithrombin. 
     
     
         2 . The TAT assay reagent according to  claim 1 , wherein the assay reagent is designed to achieve a pH of 5.8 to 6.6 during the assay. 
     
     
         3 . The TAT assay reagent according to  claim 2 , comprising:
 a second reagent comprising:
 latex particles coupled to the antibody which binds to the antithrombin part of the TAT complex and recognizes the complex and 
 latex particles coupled to the antibody which binds to the thrombin part of the TAT complex and recognizes the complex; and 
 a first reagent comprising a buffer solution at a pH of 5.8 to 6.6. 
   
     
     
         4 . A method for measuring TAT complexes in a sample separated from a living body, wherein TAT is measured by latex agglutination assay using the TAT assay reagent according to  claim 1 . 
     
     
         5 . A method for screening an antibody for use in the TAT assay of a sample separated from a living body by latex agglutination assay, the method comprising:
 preparing candidate antibodies;   allowing the candidate antibodies to react with a certain amount of free antithrombin;   subjecting the thus-obtained reaction liquids to an enzyme immunoassay using a TAT-immobilized substrate to quantify the reactivity of the antibodies to free antithrombin;   comparing the reactivity of the antibodies to free antithrombin with that to TAT; and   selecting an antibody having a reactivity to TAT that is 100 or more times higher than the reactivity to free antithrombin.   
     
     
         6 . A thrombin-antithrombin complex (TAT) assay reagent, comprising:
 a first antibody bound to a latex particle which binds to the antithrombin part of the TAT complex and recognizes the complex; and   a second antibody bound to a latex particle which binds to the thrombin part of the TAT complex and recognizes the complex;   
       wherein the assay reagent is designed to achieve a pH of 5.8 to 6.6 during the assay. 
     
     
         7 . The TAT assay reagent according to  claim 6 , comprising:
 a second reagent comprising:
 latex particles coupled to the first antibody and 
 latex particles coupled to the second antibody; and 
   a first reagent comprising a buffer solution at a pH of 5.8 to 6.6.   
     
     
         8 . A method for measuring TAT complexes in a sample separated from a living body, comprising measuring TAT by performing latex immunoagglutination reaction under a condition of pH 5.8 to 6.6 using the TAT assay reagent according to  claim 6 .