Complex-specific antibodies and antibody fragments and its use

Abstract

The present invention provides antibodies and fragments thereof that specifically detect the complex of a specific cognate antigen-binding moiety, in particular antibodies, and its antigen. The antibodies of the present disclosure do not bind either said cognate antigen binding moiety or said antigen alone and this can be used e.g. to directly detect antigen-bound antigen-binding moieties. Further disclosed are methods for production and use of said antibodies and antibody fragments.

1 . A method of detecting a complex of a specific cognate antibody or fragment thereof and its antigen, in a sample, the method comprising the steps of:
 a) contacting said sample with an isolated antibody or fragment thereof wherein said isolated antibody or fragment thereof specifically binds said complex and does not bind either said specific cognate antibody or said antigen alone, and   b) detecting said isolated antibody or fragment bound to said complex.   
     
     
         2 . A method for quantifying or monitoring levels of a complex of a specific cognate antibody or fragment thereof and its antigen in a sample, said method comprising detecting the complex according to  claim 1 , and correlating said isolated antibody or fragment thereof bound to said complex with the concentration of the antigen-bound cognate antibody. 
     
     
         3 . A method of detecting an unbound specific cognate antibody or fragment thereof, in a sample, the method comprising the steps of
 a) immobilizing the antigen of said specific cognate antibody,   b) bringing said immobilized antigen in contact with said sample, and   c) detecting the complex formed between said specific cognate antibody and its antigen with an isolated antibody or fragment thereof which specifically binds to said complex and does not bind either said specific cognate antibody or said antigen alone.   
     
     
         4 . A method for quantifying or monitoring levels of an unbound specific cognate antibody or fragment thereof in a sample, said method comprising detecting the unbound specific cognate antibody or fragment thereof according to  claim 3 , and correlating the complex formed between said immobilized antigen and said specific cognate antibody with the concentration of the unbound cognate antibody in the sample. 
     
     
         5 . A kit comprising one or more antibodies, or fragments thereof, which specifically bind to the complex of a specific cognate antibody and its antigen, and do not bind either said specific cognate antibody or said antigen alone and at least one reagent or device necessary for the detection of said specific cognate antibody and its antigen. 
     
     
         6 . A lateral flow device comprising one or more antibodies, or fragments thereof, which specifically bind to the complex of a specific cognate antibody and its antigen, and do not bind either said specific cognate antibody or said antigen alone and a lateral flow membrane.