Methods for differentially detecting a multimeric form from a monomeric form of a multimer-forming polypeptide through three-dimensional interactions

A method for differentially detecting a multimeric form from a monomeric form of a multimer-forming polypeptide in a biosample, comprising:

• (a) preparing a carrier-capturing antibody conjugate by binding a capturing antibody to the surface of a solid phase carrier in a three dimensional manner, wherein the capturing antibody is capable of recognizing an epitope on the multimer-forming polypeptide, and the solid phase carrier has a three dimensional structure;
• (b) preparing a detection antibody, wherein the epitope recognized by the capturing antibody has an amino acid sequence which overlaps, but is not identical to, with that of the epitope recognized by the detection antibody so that the capturing antibody and detection antibody when bound to their epitopes induce steric hindrance or are competitive in binding;
• wherein the epitope recognized by the capturing antibody and the epitope recognized by the detection antibody are not repeated in the multimer-forming polypeptide, and wherein the detection antibody has a label generating a detectable signal;
• (c) contacting simultaneously the carrier-capturing antibody conjugate and the detection antibody to the biosample;
• (d) separating carrier-capturing antibody-multimeric form-detection antibody complexes and carrier-capturing antibody-monomeric form complexes, from detection antibody-monomeric form complexes by washing out detection antibody-monomeric form complexes;
• and
• (e) detecting the formation of a carrier-capturing antibody-multimeric form-detection antibody complex by measuring a signal generated from the label linked to the detection antibody.