Dictionary > Opsonin


noun, plural: opsonins
Any substance (e.g. antibody) that binds to the surface of a particle (e.g. antigen) to enhance the uptake of the particle by a phagocyte (e.g. macrophage)
An opsonin refers to any substance that enhances phagocytosis. An example of a natural opsonin is certain antibodies. Antibodies are glycoproteins produced by B cells. Their main function is to protect the body from foreign agents (called antigens) through an immune response against the antigens. There are different types of antibodies. They may be grouped based on their mode of action or by the reactions produced with the corresponding antigens. Some of these groups are agglutinins, bacteriolysins, haemolysins, opsonins, and precipitins. Antibodies that act as opsonins bind to the surface of an antigen and in doing so result in the phagocytosis of the antigen by a phagocyte, such as a macrophage.
Opsonins are essential in immunological protection of the host against pathogenic bacteria. Opsonins in the surface of the antigen serve as “flags” to indicate that the antigen needs to be destroyed by the action of the immune system. Opsonins also act on dead cells, marking them up for recycling.
The process wherein a substance is chemically modified to become delicious to a phagocyte is referred to as opsonization.
Word origin: Greek opsōneîn (“to prepare for eating”)
See also:

You will also like...

Schematic diagram of bacterial lactose operon
Gene Action – Operon Hypothesis

Learn how the way genes control and determine every aspect of the body. This lesson uses lac operon as an example. ..


Types and Causes of Brain Damage
Types and Causes of Brain Damage

This tutorial describes the different types and causes of brain damage. Find out how genetics, physical injury, lack of ..

Early Earth
The Origins of Life

This tutorial digs into the past to investigate the origins of life. The section is split into geological periods in the..

Pikas are an indicator species for climate change
Indicator Species and Endangered Species

Certain species are capable of expressing characteristics indicative of the state of the ecosystem they occupy. They are..

An artistic depiction of Dunkleosteus fish

The sea was teeming with life. Eventually, through reproduction and continued variation, fish came about. There are over..

Fossil trilobite imprint in the sediment

There are more species of insects than any other species combined. This surely illustrates that insects have the selecti..