1. Proteins in blood serum that enhance the ability of phagocytes to engulf and destroy pathogens; antibodies or complement components that mark foreign substances for destruction.
Usage: medical/immunology; plural form; singular is opsonin; technical term used in immunology and microbiology

Examples

• Opsonins coat the surface of bacteria, making them easier targets for white blood cells.
• The immune system produces opsonins to mark pathogens for destruction.
• Complement proteins function as opsonins in the innate immune response.
• Opsonins bind to antigens and facilitate phagocytosis by immune cells.
• The presence of specific opsonins in the blood indicates prior exposure to certain infections.