KA 2: Specific Defences KA2: Specific Defences (e) Autoimmunity & Allergies (a) Immune Surveillance KA2: Specific Defences (b) Clonal Selection Theory (d) Immunological Memory (c) T and B Lymphocytes

By the end of this section you will be able to ….. KA 2a+b: Specific Defences By the end of this section you will be able to ….. State what is meant by Immune Surveillance State what is meant by Clonal Selection Theory Describe the specificity of lymphocyte receptors 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. (b) Clonal selection theory. Lymphocytes have a single type of membrane receptor specific for one antigen. Antigen binding leads to repeated lymphocyte division resulting in a clonal population of lymphocytes. (c) T and B lymphocytes. Lymphocytes respond specifically to antigens on foreign cells, cells infected by pathogens and toxins released by pathogens. T-lymphocytes have specific surface proteins that allow them to distinguish between the surface molecules of the body’s own cells and cells with foreign molecules on their surface. Immune system regulation failure leads to T -lymphocyte immune response to self antigens (auto immune disease). Allergy is a hypersensitive B lymphocyte response to an antigen that is normally harmless. T-lymphocytes. One group of T lymphocytes destroy infected cells by inducing apoptosis. Another group of T lymphocytes secrete cytokines that activate B lymphocytes and phagocytes. When pathogens infect tissue, some phagocytes capture the pathogen and display fragments of its antigens on their surface. These antigen presenting cells activate the production of a clone of T lymphocytes that move to the site of infection under the direction of cytokines. B lymphocytes . Each B lymphocyte clone produces a specific antibody molecule that will recognise a specific antigen surface molecule on a pathogen or a toxin. Antigen -antibody complexes may inactivate a pathogen or toxin or render it more susceptible to phagocytosis. In other cases the antigen -antibody complex stimulates a response which results in cell lysis. B lymphocytes activated by antigen presenting cells and T lymphocytes produce a clone of B lymphocytes that secrete antibodies into the lymph and blood where they make their way to the infected area. (d) Immunological memory. 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.

3 Lines of Defence The body employs 3 lines of defence: Line of defence Type of defence Method 1st Non-specific Physical & chemical barriers 2nd The inflammatory response and action of phagocytes and natural killer cells 3rd Specific Action of T- and B- lymphocytes KA 1 KA 2

What do these pictures have in common?

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 REMEMBER: mast cells -> cytokines -> attract phagocytes -> cytokines -> specific immune response

The many types of White blood cells AKA phagocyte

Lymphocytes

Lymphocytes Lymphocytes originate from stem cells in the bone marrow. Some lymphocytes pass to the thymus gland where they develop into T-lymphocytes. Those that remain and mature in the bone marrow become B-lymphocytes.

What do you remember about ANTIGENS? An antigen is a protein molecule that by its presence, stimulates an immune response from lymphocytes, as it is recognised as “foreign”. Viruses, bacteria, toxins, cancer cells, transplanted cells can all act as antigens Every antigen is different.

So what type of response do we need, if we ever get infected? Think: Numbers of cells Type of lymphocyte made We have to have ENOUGH lymphocytes to fight the pathogen! We have to have the CORRECT lymphocyte to fight the pathogen! Clonal selection theory: Only ONE lymphocyte is selected and cloned!

Clonal Selection Theory The body possess trillions of different lymphocytes. Each lymphocyte has several copies of a single type of membrane receptor specific for one antigen. (An antigen is a protein molecule which is recognised as ‘foreign’ and stimulates an immune response from lymphocytes) Pool of lymphocytes showing a variety of antigen receptors

Clonal Selection Theory Video! When the antigen is specific to the receptor on a lymphocyte, they will bind. This antigen binding ‘activates’ the lymphocyte and leads to repeated lymphocyte division resulting in a clonal population of lymphocytes. Both B- and T-lymphocytes can undergo clonal selection. receptor

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

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?

By the end of this section you will be able to ….. KA 2c: Specific Defences By the end of this section you will be able to ….. State 3 times lymphocytes will specifically launch an immune attack Name the 2 types of T-lymphocytes State the molecule produced by T-lymphocytes State the effect of T lymphocytes producing this molecule State what is meant by an antigen presenting cell State what happens to both T- and B-lymphocytes once they have become activated State how each type of cell becomes activated State the molecule produced by B-lymphocytes State 3 effects of B lymphocytes producing this molecule 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. (b) Clonal selection theory. Lymphocytes have a single type of membrane receptor specific for one antigen. Antigen binding leads to repeated lymphocyte division resulting in a clonal population of lymphocytes. (c) T and B lymphocytes. Lymphocytes respond specifically to antigens on foreign cells, cells infected by pathogens and toxins released by pathogens. T-lymphocytes have specific surface proteins that allow them to distinguish between the surface molecules of the body’s own cells and cells with foreign molecules on their surface. Immune system regulation failure leads to T -lymphocyte immune response to self antigens (auto immune disease). Allergy is a hypersensitive B lymphocyte response to an antigen that is normally harmless. T-lymphocytes. One group of T lymphocytes destroy infected cells by inducing apoptosis. Another group of T lymphocytes secrete cytokines that activate B lymphocytes and phagocytes. When pathogens infect tissue, some phagocytes capture the pathogen and display fragments of its antigens on their surface. These antigen presenting cells activate the production of a clone of T lymphocytes that move to the site of infection under the direction of cytokines. B lymphocytes . Each B lymphocyte clone produces a specific antibody molecule that will recognise a specific antigen surface molecule on a pathogen or a toxin. Antigen -antibody complexes may inactivate a pathogen or toxin or render it more susceptible to phagocytosis. In other cases the antigen -antibody complex stimulates a response which results in cell lysis. B lymphocytes activated by antigen presenting cells and T lymphocytes produce a clone of B lymphocytes that secrete antibodies into the lymph and blood where they make their way to the infected area. (d) Immunological memory. 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.

When do lymphocytes respond? Lymphocytes respond specifically to: Antigens on foreign cells Cells infected by pathogens Toxins released by pathogens

T-lymphocytes One group of T lymphocytes destroy infected cells by inducing apoptosis (Cytotoxic T cells)

T-lymphocytes Another group of T lymphocytes (Helper T cells) secrete cytokines that activate B lymphocytes and phagocytes.

Antigen presenting cells

Antigen presenting cells

T-lymphocytes One group of T lymphocytes destroy infected cells by inducing apoptosis (Cytotoxic T cells) Another group of T lymphocytes (Helper T cells) secrete cytokines that activate B lymphocytes and phagocytes. When pathogens infect tissue, some phagocytes capture the pathogen and display fragments of its antigens on their surface. These antigen presenting cells activate the production of a clone of T lymphocytes that move to the site of infection under the direction of cytokines.

B-lymphocytes Each B lymphocyte clone produces a specific antibody molecule that will recognise a specific antigen surface molecule on a pathogen or a toxin.

Inactivate a pathogen or toxin http://www.youtube.com/watch?v=lrYlZJiuf18 Inactivate a pathogen or toxin Render it more susceptible to phagocytosis

Stimulate a response which results in cell lysis.

B-lymphocytes Each B lymphocyte clone produces a specific antibody molecule that will recognise a specific antigen surface molecule on a pathogen or a toxin. Antigen - antibody complexes may: Inactivate a pathogen or toxin Render it more susceptible to phagocytosis Stimulate a response which results in cell lysis.

B-lymphocytes Each B lymphocyte clone produces a specific antibody molecule that will recognise a specific antigen surface molecule on a pathogen or a toxin. Antigen - antibody complexes may: Inactivate a pathogen or toxin Render it more susceptible to phagocytosis Stimulate a response which results in cell lysis. B lymphocytes (that have been activated by antigen presenting cells and T lymphocytes) produce a clone of B lymphocytes that secrete specific antibodies into the lymph and blood where they make their way to the infected area.

Can you now …. State 3 times lymphocytes will specifically launch an immune attack Name the 2 types of T-lymphocytes State the molecule produced by T-lymphocytes State the effect of T lymphocytes producing this molecule State what is meant by an antigen presenting cell State what happens to both T- and B-lymphocytes once they have become activated State how each type of cell becomes activated State the molecule produced by B-lymphocytes State 3 effects of B lymphocytes producing this molecule

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? 3. Name 3 possible effects of the protein produced by B-lymphocytes The lymphocyte involved in cell destruction is the cytotoxic T cell. It induces apoptosis in infected cells Antibodies specific to the antigen

Quick Questions Inactivate a pathogen or toxin 3. Name any possible effect of the protein produced by B-lymphocytes Inactivate a pathogen or toxin Render it more susceptible to phagocytosis. Stimulate a response which results in cell lysis.

By the end of this section you will be able to ….. KA 2d: Specific Defences By the end of this section you will be able to ….. State 2 cells which become memory cells State what is meant by immunological memory State 3 differences between the first and second immune response 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. (b) Clonal selection theory. Lymphocytes have a single type of membrane receptor specific for one antigen. Antigen binding leads to repeated lymphocyte division resulting in a clonal population of lymphocytes. (c) T and B lymphocytes. Lymphocytes respond specifically to antigens on foreign cells, cells infected by pathogens and toxins released by pathogens. T-lymphocytes have specific surface proteins that allow them to distinguish between the surface molecules of the body’s own cells and cells with foreign molecules on their surface. Immune system regulation failure leads to T -lymphocyte immune response to self antigens (auto immune disease). Allergy is a hypersensitive B lymphocyte response to an antigen that is normally harmless. T-lymphocytes. One group of T lymphocytes destroy infected cells by inducing apoptosis. Another group of T lymphocytes secrete cytokines that activate B lymphocytes and phagocytes. When pathogens infect tissue, some phagocytes capture the pathogen and display fragments of its antigens on their surface. These antigen presenting cells activate the production of a clone of T lymphocytes that move to the site of infection under the direction of cytokines. B lymphocytes . Each B lymphocyte clone produces a specific antibody molecule that will recognise a specific antigen surface molecule on a pathogen or a toxin. Antigen -antibody complexes may inactivate a pathogen or toxin or render it more susceptible to phagocytosis. In other cases the antigen -antibody complex stimulates a response which results in cell lysis. B lymphocytes activated by antigen presenting cells and T lymphocytes produce a clone of B lymphocytes that secrete antibodies into the lymph and blood where they make their way to the infected area. (d) Immunological memory. 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.

From primary to secondary 

Primary response When a pathogen infects the body, it takes time to raise an immune response: It takes time to: Select the correct T and B cells For these cells to undergo clonal selection Produce the specific antibodies. This is called the primary response, and very often it is too slow to prevent the pathogen from causing illness.

Compare the 1st and 2nd response

Secondary response Some of the T and B lymphocytes, which were produced to antigens by clonal selection after the first exposure, survive long term as MEMORY CELLS. A secondary exposure to the same antigen is recognised by these memory cells and this rapidly gives rise to a new clone of lymphocytes producing a rapid and greater immunological response compared to the first response: Antibody production is much more rapid The concentration of antibodies produced is higher The higher concentration of antibodies is maintained for a longer time.

Can you now …. State 2 cells which become memory cells State what is meant by immunological memory State 3 differences between the first and second immune response

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 for a longer time

Quick Questions Name cell Q Describe 2 functions of cell P as shown in the diagram. Name cell P Antibody producing B lymphocyte Recognise foreign antigens and copy itself to produce a clonal population of B cells / become memory cells B Lymphocyte

By the end of this section you will be able to ….. KA 2e: Specific Defences By the end of this section you will be able to ….. Name the cell involved with allergic reactions Describe the role of T lymphocytes in recognising self and non-self antigens Explain what is meant by an autoimmune disease in relation to lymphocyte regulation Name the cell involved with autoimmune diseases State what is meant by the term ‘allergy’ and give examples of common allergic reactions 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. (b) Clonal selection theory. Lymphocytes have a single type of membrane receptor specific for one antigen. Antigen binding leads to repeated lymphocyte division resulting in a clonal population of lymphocytes. (c) T and B lymphocytes. Lymphocytes respond specifically to antigens on foreign cells, cells infected by pathogens and toxins released by pathogens. T-lymphocytes have specific surface proteins that allow them to distinguish between the surface molecules of the body’s own cells and cells with foreign molecules on their surface. Immune system regulation failure leads to T -lymphocyte immune response to self antigens (auto immune disease). Allergy is a hypersensitive B lymphocyte response to an antigen that is normally harmless. T-lymphocytes. One group of T lymphocytes destroy infected cells by inducing apoptosis. Another group of T lymphocytes secrete cytokines that activate B lymphocytes and phagocytes. When pathogens infect tissue, some phagocytes capture the pathogen and display fragments of its antigens on their surface. These antigen presenting cells activate the production of a clone of T lymphocytes that move to the site of infection under the direction of cytokines. B lymphocytes . Each B lymphocyte clone produces a specific antibody molecule that will recognise a specific antigen surface molecule on a pathogen or a toxin. Antigen -antibody complexes may inactivate a pathogen or toxin or render it more susceptible to phagocytosis. In other cases the antigen -antibody complex stimulates a response which results in cell lysis. B lymphocytes activated by antigen presenting cells and T lymphocytes produce a clone of B lymphocytes that secrete antibodies into the lymph and blood where they make their way to the infected area. (d) Immunological memory. 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.

Collect a set of cards and decide if each card is TRUE or FALSE TASK: Collect a set of cards and decide if each card is TRUE or FALSE

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. 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. 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. 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.

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.

Type 1 diabetes Destruction of Beta cells

Graves disease When an auto-immune attack starts on your thyroid, it responds by producing more of its hormones.  At the same time the antibodies attacking your thyroid gland also attack the tissues around your eyes. causes the muscles and soft tissues of the eye socket to swell

Psoriasis skin condition that causes red, flaky, crusty patches of skin covered with silvery scales The skin cells in people with psoriasis grow at an abnormally fast rate, which causes the buildup of psoriasis lesions.

Inflammation of the lining of the digestive system (IBD) Crohn’s diseases In Crohn's disease, a rogue immune system attacks the digestive tract, causing inflammation and tissue damage.

Multiple Sclerosis

Confusing self and non-self

Confusing self and non-self antigens T-lymphocytes have specific surface proteins that allow them to distinguish between the surface molecules of the body’s own cells and cells with foreign molecules on their surface. However, sometimes immune system regulation can fail. This is when 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. T –lymphocytes launch an immune response to self-antigens. This is called autoimmunity. Autoimmune disorders include: Rheumatoid arthritis Type 1 diabetes Multiple sclerosis.

What happens during hayfever?

Anaphylactic shock Anaphylactic shock is a life-threatening allergic response to an allergen that has been injected (for example, penicillin or bee venom) or consumed (for example, peanuts). The person is so allergic to the antigenic substance that many mast cells respond and secrete large quantities of histamine and other inflammatory agents. This triggers sudden dilation of peripheral blood vessels, loss of much circulatory fluid to surrounding tissues and a drop in blood pressure. Death can occur within minutes of exposure to the allergen.

Allergies Allergic reaction occur when hypersensitive B lymphocytes launch an immune response against an antigen that is normally harmless, such as dust, pollen and feathers etc. or even antibiotics such as penicillin. The hypersensitive B-lymphocytes release antibodies which cause mast cells to release histamine. This leads to symptoms such as congestion, constriction of bronchioles or in severe cases, a sudden and dramatic drop in blood pressure.

1. 2. 3.

Can you now …. Name the cell involved with allergic reactions Describe the role of T lymphocytes in recognising self and non-self antigens Explain what is meant by an autoimmune disease in relation to lymphocyte regulation Name the cell involved with autoimmune diseases State what is meant by the term ‘allergy’ and give examples of common allergic reactions

Key area 1+2 what you should know

Revision of Key Area 2

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 cytotoxic T 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?

Answers B and T lymphocytes The thymus gland To activate B lymphocytes and phagocytes Antigens The binding of a lymphocyte receptor to an antigen activates the lymphocyte which leads to it dividing producing a clonal population of lymphocytes. a) An immune response against self antigens by T lymphocytes b) rheumatoid arthritis / Type 1 diabetes / multiple sclerosis. 7) Induces apoptosis (programmed cell death) 8) a) Specific antibodies that recognise a specific antigen b) when an antibody-antigen complex is formed the pathogen is inactivated OR it renders it more susceptible to phagocytosis OR stimulates a response which results in cell lysis 9) Primary exposure 10) Secondary exposure 11) Memory cells 12) The second response produces a larger concentration of antibodies and does it faster than the first response

MCQ Quiz  /8

1. 2.

3. 5. 4. 6.

7. 8.

Extended Answer Question Describe how immunity is naturally acquired. (6 marks)

1 Active immunity is when the body makes its own antibodies in response to an infection/pathogen/disease. 2 Invading viruses/bacteria/microbes contain antigens (on their surface). 3 Lymphocytes recognise foreign/non-self-antigens (on the invading microbes). 4 B lymphocytes produce antibodies. 5 Antibodies are specific/have receptor sites which bind/attach to foreign antigens. 6 T lymphocytes kill the infected cell/produce chemicals that destroy microbes. 7 Following an infection memory cells are produced/remain in the body. 8 These detect a reinvading microbe and destroy it (before it can cause infection). 9 This (secondary) response is faster/stronger (than the first primary response). 6 marks

Key Area 2: Past Papers Paper (new higher human biology) Section Don’t forget you can do the Key Area 1 Questions again! Yey  Key Area 2: Past Papers Paper (new higher human biology) Section Question 2015 1 19, 20 (PS) 2 11b, 12 (PS) Specimen 18, 20 (PS) Exemplar 12c only Yellow Booklet Paper (revised higher human biology) Section Question 2015 2 12c, 13 (PS) 2013 1 28 (PS) 13c 2012 30 13a-c Red Booklet