CELL comparison

1. CELL comparison starter

2. CELL comparison starter

3. Immune system diseases Non specific immunity Disease survival mechanisms Physical & chemical barriers Infectious Disease Inflammatory Transmission Epidemiology Non-specific Cellular response Specific immunity Public Health Vaccination Immunological surveillance T cells B cells Clonal Selection theory Memory cells Big picture

4. Learning outcomes • Recap clonal selection theory • Explain importance of antigen presenting cells in the activation of cells • Use the pattern of the response curve to demonstrate the importance of Memory cells

5. Clonal selection theory • The body has a large number of lymphocytes each with a single type of membrane receptor specific for one antigen. • When a receptor is activated by the binding of an antigen, the lymphocyte repeatedly divides resulting in a clonal population of lymphocytes. • To become fully activated – antigen presenting cells are needed ...... Cell division

7. Antigen presenting cells • Ingested pathogens (phagocytes like macrophages) or infected cells display fragments of the pathogen on the surface of the cell • These , research have shown, are playing an ever increasing role in the immune system, as they activate other cells.

8. Some T and B lymphocytes produced in response to antigens by clonal selection survivelong term as memory cells. A secondary exposure to the same antigen rapidly gives rise to a new clone of lymphocytes producing a rapid and greater immunological response. Memory cells

9. Primary Immune Response This is a response to an invader the First time the invader infects the body. No measurable immune response for first few days. Next 10 – 15 days antibody production grows steadily Secondary Immune Response A more rapid response to an invader the 2nd time it invades the body. Antibody production increases dramatically and in a much shorter time period.. Primary .vs. Secondary Immune Response

10. Primary .vs. Secondary Immune Response

11. Demonstrate your understanding You will be given 9 statements and a graph. You must put the statements in order and write them on the graph Do not cut the statements out

12. Primary – establishes immunological memory

13. Primary and secondary responses • Annotate your graph of the primary and secondary responses by adding the following labels: • First dose of antigen • Second dose of antigen • Time between 1st and second exposure • Primary response • Secondary response • Questions: • Compare the primary and secondary responses in terms of time taken, decline of antibodies and antibodies produced. • Memory cells are produced in the primary response, how else could these be produced without the person being infected? • Extra challenge: What causes the secondary response to occur more rapidly? LO:

14. Primary Response • Infection (Ag) • Lag phase • 3 Antibodies produced • 4 Antibody level rises • to combat infection • 5 Ag dealt with • 6 Ab level declines – short lived Antibody Concentration – Primary and Secondary Response Secondary Response After the primary response, Ab’s do not stay in blood – the level declines If the body is infected by the same Ag a second time Ab’s must be made again Re-infection causes much more rapid and a stronger immune response – concentration of Ab’s rises sooner- reaches a higher concentration – more plasma cells than in 1o response – more cells to respond to Ag; less time to produce same number of plasma cells –hence, a greater [Ab] compared to 1o response; increased affinity of Ab for Ag. This is due to the presence of memory cells (made during the primary response) – no need for antigen presentation and clonal selection Long-lived; basis of vaccination

15. The graph below shows the levels of anti-Rubella (German Measles) in the blood B Secondary Response 10000 A Primary Response 1000 Concentration of anti-Rubella antibody in the blood/arbitrary units 100 10 30 20 10 Long interval First exposure to antigen X Second exposure to antigen Y Time/days • infection, or • vaccination

16. The graph below shows the immune response of two mice exposed to a pathogen. Both mice were expose on day 0 of the experiment Mouse A Mouse A 10000 1000 Concentration of anti-Rubella antibody in the blood/arbitrary units 100 10 25 15 20 10 5 Time/days

17. Plenary: True or False? • Antibodies are produced by memory cells. • Antibodies can detect any antigen. • A antigen-antibody complex is formed when an antibody binds to a pathogen’s antigens. • Agglutination makes it easier for phagocytes to engulf pathogens. • Neutralisation only occurs with viruses. • Opsonisation causes phagocytes to swell and burst. • Antibodies can stop viruses entering host cells. • The primary immune response produces memory cells. • The secondary immune response is caused by vaccination. • The secondary immune response is quicker.

18. Summary slide Specific defences Immune surveillance • A range of white blood cells constantly circulate monitoring the tissues. • If tissues become damaged or invaded, cells release cytokines which increase blood flow resulting in specific white blood cells accumulating at the site of infection or tissue damage. • Recognition of self and non self through specific surface proteins (antigens) • Lymphocytes respond specifically to antigens on foreign cells, cells infected by pathogens and toxins released by pathogens.

19. Summary slide specific defences Clonal selection theory • The body has a large number of lymphocytes each with a single type of membrane receptor specific for one antigen. • When a receptor is activated by the binding of an antigen, the lymphocyte repeatedly divides resulting in a clonal population of lymphocytes.

20. Summary slide Specific defences Immunological memory cells • Some T and B lymphocytes produced in response to antigens by clonal selection survive long term as memory cells. • A secondary exposure to the same antigen rapidly gives rise to a new clone of lymphocytes producing a rapid and greater immunological response.