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Aims: To explain how features of adaptive immunity protect against infection

Aims: To explain how features of adaptive immunity protect against infection. Objectives; Students will be able to : explain how the innate and adaptive immune mechanisms are integrated outline the role of antibdy mediated immunity outline T cell restriction

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Aims: To explain how features of adaptive immunity protect against infection

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  1. Aims: To explain how features of adaptive immunity protect against infection • Objectives; Students will be able to : • explain how the innate and adaptive immune mechanisms are integrated • outline the role of antibdy mediated immunity • outline T cell restriction • describe the basis for immunisation to prevent infectious disease

  2. All creatures have their parasites • Humans: ~1500 species microbes • Remain an important cause of disease • Best parasites • Enter, evade detection, do little damage, leave • Worst parasites • Too much damage, they die

  3. Where to meet: ‘Armpits to anus’ • Nature needs balance with limits to damage • common cold • Most live harmlessly in hosts • Microbes multiply rapidly • 3 defences • surface • Innate • adaptive Cooperative

  4. Adaptive • Special cells take microbes to pieces and present to the immune system • antigen presenting cells ‘APC’ • Antigens: • APC presents small fragments • B cells - antibody mediated • T cells cell mediated • Where • lymphoid organs

  5. Antibodies... • Prevent microbes attaching • Clumps microbes • makes phagocytosis really easy • Activate complement drive holes in microbe • Activate complement, to cause inflammation This takes time!

  6. Antibodies • Classes: • IgM Massive in blood - powerful • IgG General workhorse in blood, leak easily • IgA Acts at surfaces esp gut, and milk • IgE Explodes with mast cells to expel parasites

  7. MHC • What • molecule unique to you alone! • Two types MHC I (all body cells) • MHC II (leukocytes only) • When • T cells recognise only antigens when presentedtogether with MHC • Why, • so that Tc cell response is restricted to infected body cells only. Free and self antigens are ignored.

  8. MHC I • TH cells only bind to leukocytes with MHC II and antigen • Why - restricts TH cells to ’help’ only the cells required for a specific response • Where - Lymphatics to interact with immune cells • T cells do not bind to free floating antigen • B cells do.

  9. Immunity to viruses • Viruses have no independent metabolic activity; so must replicate inside living host cells. • Cytotoxic T cells, and natural killer cells recognize virus infected body cells and destroy them. • T cells secrete interferon, activating other parts of the immune system, e.g. macrophages

  10. Immunity to viruses

  11. Immunocompromised • Barrier • Mucosa - chemotherapy, I/V catheters • Neutropaenia • Leukaemia, chemotherapy, • Cell dysfunction • Immunosuppressive drugs, Hodgkin disease • Humoral dysfunction • Burns, nutrition • Spleen dysfunction • sickle cell disease, trauma

  12. Whatabout • Nutrition • Genetic factors • Age, Sex • Hormones and stress • Others • Environmental - pollution • Chronic disease • Fatigue

  13. Vaccines • Gain exposure to antigen and acquire memory • Live attenuated • Yellow fever • Inactivated whole organism • Hepatitis A • Purified sub-unit - Recombinant DNA • Hepatitis B • Toxoid • Tetanus

  14. Immunity Innate Acquired Passive Active Artificial Natural Artificial Natural Breast milk Inject Immunoglobulins Administer pathogens Exposure to disease

  15. Useful reading: http://health.nih.gov/ http://newscenter.cancer.gov/sciencebehind/immune/immune00.htm Mims, C. (2000). The war within us Academic press

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