Unit 4 - Immunology and Public Health

Unit 4 – Immunology and Public Health 1. The Immune System 2. Infectious Diseases and immunity Non-specific defences Specific cellular defences Transmission and control Active Immunisation and Vaccination and the evasion of immune responses

By the end of this section you will be able to ….. 1. The Immune System b) specific cellular defences By the end of this section you will be able to ….. describe what is meant by Immune Surveillance describe what is meant by Clonal Selection Theory describe the specificity of lymphocyte receptors

What do these pictures have in common?

Immune surveillance A range of white blood cell constantly circulate and monitor the tissues. If tissues become damaged or invaded, these cells release cytokines, which increase blood flow resulting in specific white blood cells accumulating at the site of infection or tissue damage.

Lymphocytes Lymphocytes are made in the bone marrow from stem cells. Some leave and mature in the thymus gland (T-lymphocytes) Whilst others remain and mature in the bone marrow (B-lymphocytes)

Lymphocytes The body has a vast array of lymphocytes and each with different SPECIFIC functions. It is therefore important for the body to create as many lymphocytes as possible since a specific response is needed for each type of infection! THINK/PAIR/SHARE: What do you think we mean by a “clonal population of lymphocytes”?

Clonal Selection Theory https://www.youtube.com/watch?v=HUSDvSknIgI&feature=related Pool of lymphocytes showing a variety of antigen receptors

Clonal selection theory

Clonal Selection Theory The body has a vast array of lymphocytes, each with a single type of membrane receptor specific for one antigen. When the receptor on a lymphocyte binds to a non-self antigen, it becomes activated. This leads to the lymphocyte dividing repeatedly and cloning themselves Thus, a clonal population of lymphocytes is produced.

Clonal Selection Theory Surface receptor Only B-Lymphocyte ____ is activated because the a_____ is complementary and s_____ to cell Y receptor shape. Y antigen specific

Clonal Selection Theory – EXPONENTIAL GROWTH What would you rather do? work for a flat rate of £100 per week OR start earning 1p but the salary doubles each week. OPTION 1 – you make £5,200 per year. OPTION 2 – you make £5,242.88 after only 20 weeks. After 52 weeks it becomes an inconceivable amount of money.

Can you now …. describe what is meant by Immune Surveillance describe what is meant by Clonal Selection Theory describe the specificity of lymphocyte receptors