The Immune Response

1. The Immune Response

2. Leucocytes: white blood cells. Some secrete substances which destroy pathogens, others engulf and digest. • Lymphocytes: • Approx 20-30% of all white blood cells (mainly T cells and B cells) • Phagocytes: • Cells which engulf & digest mirco-organisms / cell debris. • Macrophages: develop from some leucocytes. More specific. The LYMPHATIC SYSTEM

3. lymph capillaries  lymph vessels lymph nodes • Lymph Nodes: • neck, armpits, groin & around AC • bean shaped (1 – 25mm) • Acts as a filter containing masses of lymphoid tissue (lymphocytes, macrophages & plasma cells) The LYMPHATIC SYSTEM

4. Role of Lymphatic System • Large particles (e.g. bacteria) trapped in fibre mesh and destroyed by macrophages via Phagocytosis • Lymphocyte production increases and lymph nodes become swollen on infection • Immune response • Lymphoid Organs • Tonsils: 3 sets in pharynx • Spleen: filters blood (like lymph nodes) • Thymus: immunity (behind sternum) The LYMPHATIC SYSTEM

5. Homeostatic mechanism (very specific) • 2 Part immune response • Humoralresponse / antibody-mediated immunity • Special proteins (antibodies) produced from B-Cells in Lymphoid Tissue • Cell mediated response • Special lymphocytes produced from T-Cells in Lymphoid Tissue The Immune Response • B and T cells are lymphocytes formed in red bone marrow but mature in two diff. places • B cells: bone marrow • T cells: Thymus

6. Antigens: • Generally • large molecules (proteins carbs, lipids or nucleic acids) • Whole micro organisms (virus particle & bacteria) • Part of a microorganism (cell wall, flagella) • Toxins (from bacteria) • Foreign material The Immune Response

7. Antibodies: • Special Proteins (Immunoglobulins – IgA, IgD, IgE, IgG, IgM) made in response to a non-self antigen • Combines to form an antigen-antibody complex • Specific active site (only one specific antigen can combine with any antibody) • Released into blood / lymph The Immune Response

8. Antibodies can: • Combine and inactivate the antigen by inhibiting the reactions with other cells (foreign enzyme / bacterial toxin) • Bind to surface, prevent from entering cells (viruses) • Coats bacteria, more easily consumed by phagocytes • Agglutination (antigens clump together) • Dissolve antigen • - If antigen is soluble, reacts to become insoluble. (easier to be consumed) The Immune Response

9. Antibody – mediated Immunity (B Cells) • Thousands of diff types of B Cells • When activated (sensitised) by an antigen, B Cells enlarge and divide clones • Most clones: plasma cells which secrete a specific antibody • Some become memory cells and spread out to all body tissues  Allows faster response in future. The Immune Response

10. Cell – mediated Immunity (T Cells) • Thousands of diff types of T Cells • When activated (sensitised) by an antigen, T Cells enlarge and divide clones • Most clones: Become a specialised T Cell • Some become memory cells and spread out to all body tissues  Allows faster response in future. The Immune Response

11. Killer T Cells • - Attach to antigen and destroy it • Helper T Cells • - Secretes a substance that sensitises more lymphocytes • - Secretes a substance that attracts more macrophages • - Secretes a substance that enhances macrophage activity • Suppressor T Cells • - Release substances that inhibit T and B cell activity, slowing down immune response (when immune response is finished) The Immune Response

12. The Immune Response

13. Immunity: resistance to infection by invading micro organisms • Immunisation: process of acquiring immunity (Natural or artificial) • Passive Immunity: Individual given antibodies produced elsewhere. • Natural (from mother) or artificial (injection) • Short lived but fast response • Active Immunity: Individual exposed to foreign antigen the manufactures antibodies in defence • Natural (actually infected) or artificial (injection) • Long lasting Types of Immunity

14. Vaccines • Vaccination: Artificial Active Immunity. (Antigen introducedindividual produces antibody doesn’t suffer symptoms) • 4 Main vaccine types: • Micro-organisms/Viruses of reduced virulence (attenuated): Decreased ability to produce disease symptoms (often using recombinant DNA) • e.g. polio, TB, rubella, measles, mumps, yellow fever, flu (nasal spray) • Dead/Inactivatedmicro organisms / viruses: not as prolonged • e.g. cholera, typhoid, whooping cough, flu (shot) • Toxoids: Inactivated toxins from bacteria • e.g. diphtheria, tetanus • Sub-unit Vaccine: fragment of organism • e.g. Hep B • Delivery: syringe, ingested, nasal spray, skin patches, Types of Immunity

15. Risks • Allergic reaction • Possible cross-species disease introduction (while immunising an individual it is possible that the vaccine also contains strains on another infectious disease as a result of the cultural medium it was developed in) • Preservatives? Types of Immunity

16. Ethical Concerns • How was vaccine manufactured, tested and risks associated? • Manufacturing: • animal host tissue (chicken embryos - influenza, mice brains - encephalitis) • human host tissue (aborted foetus’ – rubella) • Testing: • May be tested in developing countries (exploited) • Animal testing on: mice (other mammals), fish, amphibians, birds Types of Immunity