4.1.11 Opsonins, agglutinins and Anti-toxins.

Question 1

How can antibodies act as opsonins, agglutinins and anti-toxins?

Answer 1

The way in which antibodies function can vary

Antibodies can combine with viruses and toxins of pathogens (e.g. bacteria) to block them from entering or damaging cells

Antibodies can act as anti-toxins by binding to toxins produced by pathogens (e.g. the bacteria that cause diphtheria and tetanus) which neutralises them making them harmless

Antibodies can attach to bacteria making them readily identifiable to phagocytes, this is called opsonisation.

Once identified, the phagocyte has receptor proteins for the heavy polypeptide chains of the antibodies, which enables phagocytosis to occur

Antibodies can attach to the flagella of bacteria making them less active, which makes it easier for phagocytes to do phagocytosis

Antibodies act as agglutinins causing pathogens carrying antigen-antibody complexes to clump together (agglutination).

This reduces the chance that the pathogens will spread through the body and makes it possible for phagocytes to engulf a number of pathogens at one time

Antibodies (together with other molecules) can create holes in the cell walls of pathogens causing them to burst (lysis) when water is absorbed by osmosis