The Immune Response

The LYMPHATIC SYSTEM 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 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 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 Immune Response Homeostatic mechanism (very specific) 2 Part immune response 1.Humoral response / antibody-mediated immunity Special proteins (antibodies) produced from B- Cells in Lymphoid Tissue 2.Cell mediated response Special lymphocytes produced from T-Cells in Lymphoid Tissue B and T cells are lymphocytes formed in red bone marrow but mature in two diff. places B cells: bone marrow T cells: Thymus

The Immune Response 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 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 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 Antibody – mediated Immunity (B Cells) 1.Thousands of diff types of B Cells 2.When activated (sensitised) by an antigen, B Cells enlarge and divide  clones 3.Most clones: plasma cells which secrete a specific antibody 4.Some become memory cells and spread out to all body tissues  Allows faster response in future.

The Immune Response Cell – mediated Immunity (T Cells) 1.Thousands of diff types of T Cells 2.When activated (sensitised) by an antigen, T Cells enlarge and divide  clones 3.Most clones: Become a specialised T Cell 4.Some become memory cells and spread out to all body tissues  Allows faster response in future.

The Immune Response 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

Types of Immunity 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 Vaccines Vaccination: Artificial Active Immunity. (Antigen introduced  individual produces antibody  doesn’t suffer symptoms) 4 Main vaccine types: 1.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) 2.Dead/Inactivated micro organisms / viruses: not as prolonged e.g. cholera, typhoid, whooping cough, flu (shot) 3.Toxoids: Inactivated toxins from bacteria e.g. diphtheria, tetanus 4.Sub-unit Vaccine: fragment of organism e.g. Hep B Delivery: syringe, ingested, nasal spray, skin patches,

Types of Immunity 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 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