1. Why do we have an immune system?

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

3. National Cancer Institute
Understanding Cancer and Related Topics
Understanding the Immune System
Cells of the Immune System – many cells we will look specifically at these …..
Bone graft
Macrophage
Mast cell
Eosinophil
Erythrocytes
Marrow
Basophil
Monocyte
Megakaryocyte
Bone
Hematopoietic stem cell
Multipotential
stem cell
Myeloid progenitor cell
Neutrophil
Platelets
Cells destined to become immune cells, like all blood cells, arise in your body’s bone marrow from stem cells. Some develop into myeloid progenitor cells while others become lymphoid progenitor cells.
The myeloid progenitors develop into the cells that respond early and nonspecifically to infection. Neutrophils engulf bacteria upon contact and send out warning signals. Monocytes turn into macrophages in body tissues and gobble up foreign invaders. Granule-containing cells such as eosinophils attack parasites, while basophils release granules containing histamine and other allergy-related molecules.
Lymphoid precursors develop into the small white blood cells called lymphocytes. Lymphocytes respond later in infection. They mount a more specifically tailored attack after antigen-presenting cells such as dendritic cells (or macrophages) display their catch in the form of antigen fragments. The B cell turns into a plasma cell that produces and releases into the bloodstream thousands of specific antibodies. The T cells coordinate the entire immune response and eliminate the viruses hiding in infected cells.
Lymphoid progenitor cell
Dendritic cell
T lymphocyte
B lymphocyte
Natural killer cell
NCI Web site:

4. feedback
Different type of homework – interspersed extended responses with exam style questions and finally revision tools
More understanding and Less copying of slides only those with or the summary slides only

5. The human body has the capacity to protect itself against pathogens, some toxins and cancer cells through the immune system
Glossary Terms;
Pathogen – disease causing organisms
Toxins – poisons produced by organisms
Immunity – body’s ability to resist infection by a pathogen or destroy the organism if it succeeds

6. Learning outcomes
Distinguish between the non-specific and specific immune system
Identify the three lines of defence
Explain the non-specific defences

7. Immune system organisation
Split into 2 areas –
non specific and specific
Non-specific immunity works against any type of disease-causing agent
Specific immunity works against a particular pathogen

8. Non-specific physical barriers
EPITHIAL cells
The first line of defence against infection.
Line the surfaces and cavities of the entire body.
Form sheets/ layers of closely packed cells.
SECRETIONS
Some Epithelial cells produce secretions such as enzymes, hormones and lubricating fluids that can defend against infection.
Mucus traps dirt and germs, preventing them from entering the blood.
Various glands produce antimicrobial secretions that help kill microbes.
Use jelly cubes (from an ice-cube tray) as model body cells and glitter (or similar) as bacteria/viruses/fungi. When the glitter is sprinkled on the cells it sticks and begins to penetrate the cell. Repeat the experiment and this time coating the model cells with clingfilm (to represent epithelial cells – physical barrier). The glitter cannot reach the body cells. Repeat the experiment for a third time and this time coat the clingfilm with a layer of petroleum jelly (to represent secretions). Again the glitter cannot reach the body cells – instead they become trapped by the epithelial cell secretions.

9. Other physical defences
Tiny hairs at the entrance to the nose.
Cough and sneeze reflexes.
‘Friendly’
bacteria.

10. Non-specific immunity
First line of defence are physical and chemical barriers
Line of defence
Specific (s) or non-specific (ns)
Mechanism employed
Function
1st NS
Skin barrier
Epithelial cells intact
Mucus
Cilia
Traps microbes in respiratory and gastrointestinal tract
Remove microbe by sweeping
Acid
Contains hydrochloric acid at pH which has a disinfecting action on the stomach wall and contents.
Sweat and sebaceous
Low pH inhibits microbial growth
Saliva and tears
Enzymes lysozyme digests bacterial walls so it destroys them
Remember lysozyme - ZZZZZ for sleep in your eye!

11. Immune system organisation
Second line of defence is the Inflammatory response
This occurs if the first line are breached, by a cut/ piercing or an invasion of an infectious organisms

12. Immune system organisation
Second line of defence is the Inflammatory response
This occurs if the first line are breached, by a cut/ piercing or an invasion of an infectious organisms
First line are breached, by a cut/piercing or an invasion of an infectious organisms, bacteria, trauma, toxins, heat or any other cause
Mast cells (type of white blood cell) in the connective tissue, releases histamine
Histamine causes blood vessels to become more permeable
Vasodilation of blood vessels by injured site; causing swelling due to stretchy capillary wall

13. Cytokines (cell signalling molecules – many types like TNF, IL 1-10 etc.) also released by damaged cells / tissues
Enhanced migration of phagocytes to the damaged tissue by cytokines (phagocytes move to site) – next slide
Cytokines also attract antimicrobial proteins to the infected site which amplify immune response
Cytokines attract blood clotting chemicals (complement) to injury site thus preventing any blood loss / infection to the wound and allows tissue repair to start

14. Mast cells histamine vasodilation and increased capillary permeability  secrete cytokines  phagocytosis  complement / antimicrobial proteins  clotting and tissue repair

16. The phagocyte releases more cytokines – positive feedback
phagocytosis
A phagocyte is motile (moves towards pathogen when chemicals detected or antigens). It then engulfs pathogen (endocytosis) – forming a phagocytic vesicle (vacuole) which merges with a lysosome. Lysosomes contain digestive enzymes, which disposes of the pathogen and released by exocytosis.
The phagocyte releases more cytokines – positive feedback

17. Natural killer cells 2
1. Protein from NK cell inserts a pore into the target cell membrane 1
Outer membrane on target cell 3 3
3. Signal relayed and genes switched on
protease
2. Signal molecule from NK enters cell 4
vital cell protein
4. “suicide” proteins made
5. “suicide” protein function to make degradative enzymes (protease / DNAase). Destroying vital proteins/DNA 4
Useless fragments of DNA 5
DNAase 5
Useless fragments of protein
DNA

18. Natural killer (NK) cells
Final non-specific defence
For virus and tumour cells predominantly
Distinct class of lymphocytes which can work with antibody-dependent cellular cytotoxity however they are not specific – will attack cells (decide self/foreign by lack of self antigen (MHC).
A pore released from natural killer (nk) cell
NK cell then releases signalling molecules
This signals genetic control of both self destructive enzymes being released and dna / VITAL PROTEIN breakdown
Process of “cell suicide”, PROGRAMMED CELL DEATH IS called apoptosis

19. NK CELLS Perforin Granzyme Apoptosis
Perforin released forming a pore into target cell membrane
Granzyme
Granzymes enter the cell, switch on genes
Apoptosis
Stimulating the cell to produce enzymes that degrade DNA – inducing apoptosis
Secondary affect which links to the specific immune system is both NK cells and phagocytes secrete cytokines (interleukins ) that serve to stimulate the specific immune response through the activation of T cells

20. Natural killer cells 2
1. Protein from NK cell inserts a pore into the target cell membrane 1
Outer membrane on target cell 3 3
3. Signal relayed and genes switched on
protease
2. Signal molecule from NK enters cell 4
vital cell protein
4. “suicide” proteins made
5. “suicide” protein function to make degradative enzymes (protease / DNAase). Destroying vital proteins/DNA 4
Useless fragments of DNA 5
DNAase 5
Useless fragments of protein
DNA

21. WANTED! $10,000 REWARD Phagocytes and natural killer cells
For indiscriminate killing of pathogens
Phagocytes and natural killer cells
Members of the notorious white blood cell gang
$10,000 REWARD

22. Make a comic strip for each cell – nk cell and phagocyte
Key words to include ...
Apoptosis
Exocytosis
Pore
Lysosome

23. Complement system
The presence of bacteria at the site of infection stimulates antimicrobial proteins known as ‘complement’ to arrive at the site of infection.
The complement system helps the body to rid itself of infection by amplifying the immune response.

24. Cytokines .... Made by damaged tissue / white blood cells
Enhance migration of phagocytes (chemotaxins - chemoattractants) which engulf/digest pathogen and release more cytokines
Deliver antimicrobial proteins faster which amplifies immune response
Deliver blood clotting chemicals (complement) which seals the wound and helps tissue repair
Have a dual purpose; not only in the non-specific defence but also specific defence system by triggering lymphocytes (next lesson)

25. Clotting system The final stage of inflammation is tissue repair.
What do you remember from unit 2?
What molecules involved?
What is prothrombin / fibrinogen?

26. Clotting system
Platelets form a plug to seal off the site of injury and clotting elements trigger the coagulation cascade, which strengthens the platelet plug.
remodelling takes place as the healing process winds down. The final repair may be imperfect – this results in a scar.

27. Non-specific immunity
second line of defence are inflammation cascade and cellular responses
Line of defence
Specific (s) or non-specific (ns)
Mechanism employed
Function
2nd NS
Inflammatory response
Inflammatory response initiated by histamine and serotonin release from basophils/mast cells attracts
phagocytes to infected region. Reduces spread of infection throughout organism.
Cellular response of phagocytes (phagocytosis)
Ingestion and digestion of foreign particles/microbes by neutrophils, eosinophils, monocytes and macrophages.
Cellular response of natural killer cells (NK cells)
Attack virus and cancer cells by releasing molecule which forms a pore in target cells membrane which signals apoptosis by self destroying enzymes

28. Summary slide Non-specific defences Physical defences
Epithelial cells on the body surface and cavity linings form a physical barrier (skin/trachea/oesophagus etc.)
chemical defences
Mucus membranes secrete sticky mucus trapping microorganisms
Acid from epithelial cells in stomach destroy ingested microorganisms
Skin sebaceous/sweat glands produce low pH secretions that are too low for most microbes to survive

29. Summary slide Non-specific defences Inflammatory response
Release of histamine by mast cells causes vasodilation and increased capillary permeability.
The increased blood flow and the secretion of cytokines results in the accumulation of phagocytes and the delivery of antimicrobial proteins and clotting elements to the site of infection.

30. Summary slide Non-specific defences Cellular mechanisms
A variety of specialised white blood cells provide protection against pathogens.
Phagocytes recognise surface antigen molecules on pathogens and destroy them by phagocytosis.
Natural killer (NK) cells induce the pathogen to produce self destructive enzymes in apoptosis.
Both Phagocytes and NK cells release cytokines which stimulate the specific immune response.
Complement system amplifies this immune response.