What is "agglutinin"

n. 1 A substance that causes cells to clump. 2 (context specifically English) A protein found in cow's milk.

n. an antibody that causes agglutination of a specific antigen

An agglutinin is a substance that causes particles to coagulate to form a thickened mass 1. Agglutinins can be antibodies that cause antigens to aggregate by binding to the antigen-binding sites of antibodies. Agglutinins can also be any substance other than antibodies such as sugar-binding protein lectins. Agglutinins work by clumping on particles causing the particles to change from fluid-like state to thickened-mass state. When an agglutinin is added to a uniform suspension of particles such as bacteria or blood, agglutinin binds to the agglutinin-specific structure on the particle causing the particles to aggregate and fall to the bottom leaving a clear suspension. This phenomenon known as agglutination is of great importance to the medical world as it serves as a diagnostic tool.