Patent ID: 7981690

Claim:
A method of assaying an antigen by a competitive immunoagglutination assay in a homogeneous system comprising the steps of: mixing a sample containing an antigen to be assayed, an antibody against the antigen, wherein the antibody is covalently bonded to a water soluble polymer, and fine particles carrying the same antigen as the antigen to be assayed or an analogue of the antigen, which analogue is capable of undergoing an antigen-antibody reaction with the antibody; competing an antigen-antibody reaction of the antibody between the antigen in the sample and the same antigen as the antigen to be assayed or the analogue of the antigen, both of which are carried on fine particles; and quantitatively determining the antigen to be assayed based on the degree of agglutination as a result of the antigen-antibody reaction of the antibody with the same antigen as the antigen to be assayed or the analogue of the antigen, both of which are carried on fine particles.