precipitin

An antibody that reacts with a specific soluble antigen to produce a precipitate.

An adaptation-product which is formed in the blood-serum of an animal of one species when immunized with albumins or albuminous derivatives obtained from an animal of an alien species. When the sera of the two animals are brought together a precipitate results, in the formation of which the immunizing substance plays the active and the immune substance the passive rôle.

any antibody which reacts with an antigen to form a precipitate

an antibody that causes precipitation when it unites with its antigen