Coagulation versus agglutination

Coagulation and agglutination have very little in common...

However, we often hear that when blood is typed, the sample "coagulates". However, this is a false statement. Thus:
 * Coagulation = "clotting" of blood
 * is a chain of proteolytic reactions of plasma coagulation factors. The result is the polymerization of fibrin and the formation of a clot.


 * Agglutination = clumping of blood cells
 * is an antigen-antibody reaction. Non-covalent reaction between plasma proteins and erythrocytes.