Name The Different Types Of Antibodies And Indicate Their Major Function

Question 1

What are the 5 types of antibodies and their function? Known as MADGE

Answer 1

IgA (A for preventing antigens crossing tissues) - coats epithelial membranes and prevents antigens crossing them and invading deeper tissues. Found in breast milk and saliva, effective against digestive tract pathogens.

IgD ( D for displayed on B cells) - made of B cells and displayed on their surfaces. Antigens bind here to activate B cells.

IgE (E for excess antibody due to inflammation) - found on cell membranes of, for example, basophils and mast cells, if it binds it’s antigen, it activates the inflammatory response. This antibody is often found in excess in allergy.

IgG (G for granny as live longest and attack pathogen) - the largest, longest lived and most common antibody type. It attacks many different pathogens and crosses the placenta to protect the foetus. Effective against viruses.

IgM ( M for main sign, short lived and sign of invasion) - a sign of recent invasion as they are short lived and appear first. Effective against viruses. A potent activator of complement system.

Question 2

Explain the complement system

Answer 2

A system of about 20 proteins found in the blood and tissues. It is activated by the presence of immune complexes (an antigen and antibody bound together) and by foreign sugars on bacterial cell walls.

Complement:
- binds to, and damages, bacteria, cell walls, destroying the microbe.
- binds to bacterial cell walls, stimulating phagocytosis by neutrophils and macrophages.
- attracts phagocytic cells such as neutrophils into an area of infection I.e stimulates chemotaxis.