opsonin

noun Immunology.

1. a constituent of normal or immune blood serum that makes invading bacteria more susceptible to the destructive action of the phagocytes.

noun

1. a constituent of blood serum that renders invading bacteria more susceptible to ingestion by phagocytes in the serum

n.

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