opsonin

An antibody or product of complement activation in blood serum that causes bacteria or other foreign cells to become more susceptible to the action of phagocytes.

A hypothetical substance, present in blood-serum, upon which the phagocytic action of the leucocytes is dependent.

Any antibody that causes an invading species to be more susceptible to phagocytosis

an antibody in blood serum that attaches to invading microorganisms and other antigens to make them more susceptible to the action of phagocytes