1. Unit 4 - Immunology and Public Health

2. 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

3. 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

4. What do these pictures have in common?

5. 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.

6. 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)

7. 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”?

8. Clonal Selection Theory
Pool of lymphocytes showing a variety of antigen receptors

9. Clonal selection theory

10. 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.

11. 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

12. 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, after only 20 weeks. After 52 weeks it becomes an inconceivable amount of money.

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

14. Quick Questions
Describe when a clonal population of lymphocytes would be produced in the body?
If each lymphocyte can only recognise one specific antigen, how is it possible that lymphocytes offer effective protection against a wide variety of pathogens?

15. 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 the roles of 2 types of T-lymphocytes in response to infection
describe the role of B-lymphocytes in response to infection

16. Lymphocytes Lymphocytes respond specifically to:
Antigens on foreign cells
Cells infected by pathogens
Toxins released by pathogens

17. Collect 2 lymphocyte cards
Work in pairs
One person will learn about B-Lymphocytes
The other will learn about T-Lymphocytes
You will then teach your partner about your white blood cell

18. Your teaching should allow you and the other pupil to be able to answer these questions…
B-Lymphocytes
T-Lymphocytes
Explain the link between B-lymphocytes and antibodies
What is special about these antibodies?
Describe the 2 effects of an antigen-antibody complex
Explain the role of a ‘memory B cell’
How many groups of T-lymphocytes are there?
What are the names of the 2 groups?
Explain the link between lymphocytes and apoptosis
Explain the link between lymphocytes and cytokines
Explain how phagocytes and B-lymphocytes are involved

19. B-lymphocytes
B lymphocytes are able to recognise foreign antigens and engulf them.
They then display the antigens on their surface waiting for a TH cell to release cytokines and activate it.
Some will become clone antibody-producing B cells, others become cloned memory B cells

20. Activated B lymphocytes
Activated lymphocytes can produce a protein specific to the antigen called antibodies. The antibodies are able to bind to the antigen creating an antigen-antibody complex.

21. Antibody action The binding of the antibodies causes the
inactivation of the pathogen (or the toxin it produces) and
pathogen to become more susceptible to phagocytosis

22. B-Lymphocytes extra note
A specific antibody is made by B-lymphocytes.
Antibodies are secreted into the lymph and blood where they make their way to the infected area.
The antibodies recognise a specific antigen surface.
Antibody receptor site
Antigen

23. Your teaching should allow you and the other pupil to be able to answer these questions…
B-Lymphocytes
T-Lymphocytes
Explain the link between B-lymphocytes and antibodies
What is special about these antibodies?
Describe the 2 effects of an antigen-antibody complex
Explain how role of a ‘memory B cell’
How many groups of T-lymphocytes are there?
What are the names of the 2 groups?
Explain the link between lymphocytes and apoptosis
Explain the link between lymphocytes and cytokines
Explain how phagocytes and B-lymphocytes are involved

24. T-lymphocytes
There are two different types of T-lymphocytes or T-cells. - cytotoxic T cells (TC cells) AKA Killer T cells - helper T cells (TH cells)
Cytotoxic T cells cause apoptosis of an infected cell (programmed cell death)
remember NK cells!
Helper T cells become activated when they have come into contact with a foreign antigen and produce cytokines.

25. TH Cells
As seen before, there is a vast pool of different TH cells with different forms of antigen receptors. One of them will be specific to the antigen.

26. Helper T-lymphocytes (TH Cells)
ANOTHER way helper T cells can remove pathogens is when phagocytes engulf the foreign cell
This phagocyte then presents the foreign antigen on its own surface, meaning one of the TH cells will be able to bind with it.
Antigen presenting cell

27. Helper T-Lymphocytes extra notes
When pathogens infect a tissue, some phagocytes capture the pathogen and display the it’s antigens on their surface
This display of antigen presentation, activates T-lymphocytes.
Once one version of the TH cell is activated, it goes on to multiply to give further clones of activated TH cells

28. TC cells and cancer
TC cells are also able to recognise antigens found on the surface of cancer cells. They are then able to bring about the lysis of large cancer cells.

29. Antibody Production http://www.youtube.com/watch?v=lrYlZJiuf18

30. Can you now ….
describe the roles of 2 types of T-lymphocytes in response to infection
describe the role of B-lymphocytes in response to infection

31. Quick Questions
2 types of lymphocytes are produced. Explain the role of the lymphocyte which is involved in cells self-destructing.
What is produced by B-lymphocytes during the immune response?
Name 3 possible effects of the protein produced by B-lymphocytes

32. 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 immunological memory
state the benefits of having memory cells.

33. From primary to secondary 

34. Primary response
When a pathogen infects the body, it takes time to raise an immune response and select the correct T and B cells (clonal selection) and produce antibodies.
This is called the primary response, and very often it is too slow to prevent the pathogen causing illness.

35. Secondary response
However, if the person survives, and they come across the SAME pathogen a second time, they will have a much different secondary response!
This is because the body has created MEMORY CELLS
Some of the T and B lymphocytes that were produced by clonal selection after the first exposure survive long term as MEMORY CELLS.
When the SAME foreign antigen is recognised by these memory cells a second time, they very quickly form many clones of both T cells and antibody-producing B cells.
This means that their are more antibodies produced faster and for a longer duration.
This is the secondary response.

40. Can you now …. describe what is meant by immunological memory
state the benefits of having memory cells.

41. Quick Questions
For each statement below state if it refers to the 1st or 2nd exposure of a pathogen
Larger concentration of antibodies produced
Clonal population of lymphocytes occurs faster
Memory cells are produced
Immune response is longer
Illness occurs

42. 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 the role of T lymphocytes in recognising self and non-self
explain what is meant by an autoimmune disease in relation to lymphocyte regulation
state what is meant by the term ‘allergy’ and give examples of common allergic reactions

43. Decide if each card is TRUE or FALSE
Crohns disease, type 1 diabetes, Graves disease, psoriasis and rheumatoid arthritis are examples of autoimmune diseases.
Crohns disease, type 1 diabetes, Graves disease, psoriasis and rheumatoid arthritis are examples of autoimmune diseases.
Chicken pox, CJD, legionnaires’ disease and meningitis are examples of autoimmune diseases.
Chicken pox, CJD, legionnaires’ disease and meningitis are examples of autoimmune diseases.
An autoimmune disease is caused by an overactive immune response in which the body’s own cells are destroyed.
An autoimmune disease is caused by an overactive immune response in which the body’s own cells are destroyed.
Autoimmune diseases can be caught from close contact with infected people.
Autoimmune diseases can be caught from close contact with infected people.
The statements on the left are true. The statements on the right are false.
Creutzfeldt-Jakob disease (CJD) is a rare and fatal condition that affects the brain. It causes brain damage that worsens over time.
Treatment of autoimmune disease only serves to alleviate the symptoms, it does not cure the disease.
Treatment of autoimmune disease only serves to alleviate the symptoms, it does not cure the disease.
Autoimmune diseases can be easily cured with a combination of antibiotics and anti-viral drugs.
Autoimmune diseases can be easily cured with a combination of antibiotics and anti-viral drugs.
There is no known prevention for autoimmune disease.
There is no known prevention for autoimmune disease.
Children can be vaccinated against autoimmune diseases – this prevents them from getting ill in later life.
Children can be vaccinated against autoimmune diseases – this prevents them from getting ill in later life.

44. Rheumatoid arthritis
In rheumatoid arthritis, cytokines cause inflammation which will attack the bone and cartilage in joints, causing them to be replaced with fibrous tissue which leaves the joint less mobile than before.

45. Type 1 diabetes
Destruction of Beta cells

46. Graves disease

47. Psoriasis
skin condition that causes red, flaky, crusty patches of skin covered with silvery scales

48. Inflammation of the lining of the digestive system (IBD)
Crohns diseases

49. Multiple Sclerosis

50. Confusing self and non-self
T-lymphocytes have specific surface proteins that should be able to read the surface antigens of a cell and tell if it is self or non-self.
However, sometimes T-lymphocyte regulation can fail
T-lymphocytes fail to distinguish between the surface proteins of the body’s own cells and surface proteins on foreign cells and therefore attacks body cells.
The immune response against our own self cells is called autoimmunity.
Rheumatoid arthritis
Type 1 diabetes
Multiple sclerosis.

51. Confusing self and non-self

52. Allergies
B-lymphocytes sometimes over-react to harmless substances like dust, pollen and feathers etc. or even medicines such as penicillin. The hypersensitive B-lymphocytes release antibodies which cause mast cells to release histamine. Some allergies are so severe that they can trigger anaphylactic shock where the histamine causes such a huge drop in blood pressure it can be life threatening.

53. Can you now ….
describe the role of T lymphocytes in recognising self and non-self
explain what is meant by an autoimmune disease in relation to lymphocyte regulation
state what is meant by the term ‘allergy’ and give examples of common allergic reactions

54. Questions – 12 minutes! What are the two types of lymphocytes?
Where do T lymphocytes mature?
Why are cytokines released at the site of infection?
What is the name of the proteins found on cell surfaces that trigger an immune response?
Describe clonal selection.
a) What is autoimmunity?
b) Give a condition linked to autoimmunity.
7) How does a TC cell lead to the destruction of an infected cell?
8) a) What does an activated B cell produce?
b) How do these molecules bring about destruction of a pathogen?
9) What term is used to describe the first infection of the body by a pathogen?
10) If the body is re-infected at a later date, what is this known as?
11) Which cells are central to being able to fight off re-infection?
12) How does the immune response to the second infection compare to the first?

55. Quick Questions
Choose the correct words from the box below to describe what is meant by the term allergic reaction
What cell is involved in autoimmune diseases?
Explain the role of this cell in autoimmune diseases
> Under-reacts > Hyposensitive response
> Over-reacts > Normally harmful substance
> Hypersensitive response > Normally harmless substance

56. Blood groups A, B, AB, O Rhesus –ve and Rhesus +ve

57. Blood groups!

59. Agglutination

60. Agglutination

61. Tasks
Stick in the blood group tables and answer the following below it:
Explain why a person with blood group A cannot receive a transfusion from someone with blood group AB
Explain why a person with Blood group AB can receive a transfusion from someone with blood group A

62. The Rhesus factor
In addition to having A or B antigens, some people have a further antigen on their blood cells. This is called antigen D and people who possess it are said to be rhesus positive (+ve).
Those that lack the antigen D marker are said to be rhesus negative (-ve).

63. When does the rhesus marker become a PROBLEM?
Transfusion of Rh +ve RBC to a Rh –ve person must be avoided
And a child born to parents of different rhesus factors may also be at risk…

64. When does the rhesus marker become a PROBLEM?

66. When does the rhesus marker become a PROBLEM?
The immune system of a Rh -ve recipient would respond to Rh +ve red blood cells and produce anti-D antibodies.
These antibodies would persist leaving the person sensitised.
Any further transfusion of Rh +ve RBCs to the Rh –ve recipient would result in the person suffering from sever or fatal agglutination.

67. How to test for your blood group

68. You have now completed Key Area 2 of Unit 4! 