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The Immune System

The Immune System

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The Immune System

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  1. The Immune System Immune System Diseases

  2. Non-Specific Immunity • A wide variety of factors that provide non-selective opposition to the invasion of the body by foreign protein-based substances • “Antigens”

  3. Examples of Non-Specific Immunity • Inflammation • Mechanical Barrier , ie skin • Enzyme Activity • Interferons (chemical released in response to ANY viral infection) • pH (acid and alkaline)

  4. Specific Immunity Response to a specific antigen

  5. Two Types of Specific Immune Actions

  6. Immunoglobulins = Antibodies • IgG - most abundant;crosses placenta • IgA – in plasma and mucus membrane secretions • IgD - ? • IgE – increased with allergy • IgM - largest

  7. Antigen-Antibody Complex Action Antigen is rendered harmless by one or a combination of the following Precipitation Agglutination Opsonization Neutralization

  8. Complement A series of protein enzymes that attach to antigen-antibody complexes involving IgG and IgM Immune Complexes – may damage host cells as well as antigen

  9. Two Ways to Acquire Immunity

  10. Hypersensitivity Immune response that is not needed and may cause harm

  11. Hypersensitivity: Allergy • Increased amounts of IgE • IgE and antigen attach to mast cell • Mast cell releases histamine and other inflammatory mediators • Local – asthma, hay fever, hives (urticaria), GI/food allergy • Generalized – Anaphylaxis • Systemic release of histamine causes low blood pressure and swollen airways • Is life-threatening allergic reaction!

  12. Hypersensitivity: Cytotoxic • Complement attaches to IgG or IgM antigen-antibody complex (now called an immune complex) • Individual cells are lysed (most commonly RBCs) • Examples: Rh disease (Erythroblastosis Fetalis), Transfusion reactions • Transfusion reaction may also cause anaphylaxis!

  13. Hypersensitivity: Immune Complex Mediated • Immune complexes , ie IgG or IgM with complement activated, cause damage to large area of host tissue • Examples: Glomerulonephritis, Rheumatic Fever

  14. Hypersensitivity: Cell Mediated • T-lymphocytes attack harmless antigenic substances • May take 1-2 days to develop • Examples: transplant rejection, Tb skin test

  15. Immune Deficiencies Congenital: Agammaglobinemia Acquired: • Malignancies of the bone marrow and lymphatic system • Chemotherapy • Steroids • AIDS

  16. AIDS Acquired Immune Deficiency Syndrome

  17. AIDS Etiology Human Immunodeficiency Virus (HIV)

  18. HIV can be found in all body fluids of infected persons • Transmission usually most common with infected blood, semen, and vaginal secretions • Unprotected exposure to body fluids puts everyone at risk, eg health care workers High-risk practices: • IV drug abuse • Unprotected sex (includes anal sex)

  19. High Risk Groups

  20. AIDS Pathology • Virus attaches to the CD4+ protein on T-helper cells and destroys them • Decreased T-helper cell count makes the patient prone to opportunistic infections, malignancies not normally seen in patients with intact immune systems, and direct CNS destruction

  21. AIDS Progression • HIV infection – HIV+ • Antibodies produced usually within 1-6 months of exposure • The antibodies produced cannot control the virus! • ARC – AIDS Related Complex • Enlarged lymph nodes,chronic fever and fatigue, weight loss • Full blown AIDS – opportunistic infections and malignancies, and CNS damage • Usually occurs when T-helper cell count drops to less than 500 (usual count is 800-1200)

  22. Some Opportunistic Infections Seen in AIDS

  23. Malignancies Seen in AIDS • Kaposi’s Sarcoma • Malignant nodules form on the skin and in the mouth, lymph nodes, and internal organs • Squamos cell carcinomas in the mouth, rectum, and uterine cervix

  24. AIDS Treatment Current drug regimes prevent the virus from replicating. They control the virus but do not destroy it! These drugs are very costly and have many side effects! • Reverse Transcriptase Inhibitors and Nucleoside Analogs • AZT (Zidovudine), DDI (Didanosine), 3TC (Lamivudine) • Protease Inhibitors • Fusion inhibitors Palliative Surgeries

  25. AIDS “COCKTAIL” • Truvada • A combination of Tenofovir (Viread) and Emtricitabine (Emtriva) • Works So well, it is being tried as a vaccine

  26. Implications for Health Care Professionals • Frequent Handwashing • Barrier Protection for potential body fluid exposure • Mask, gown, gloves, protective eyewear • Careful technique during invasive procedures • The odds are in your favor! • HIV is not spread by casual contact! • Handshakes, eating & drinking utensils, toilet seats, etc do not transmit HIV

  27. Hate the disease…….. But don’t hate the sick person!

  28. Autoimmunity antibodies form against body tissues

  29. Autoimmune Diseases • Systemic Lupus Erythematosus (SLE or “Lupus”) • Rheumatoid Arthritis • Multiple Sclerosis (MS) • Autoimmune diseases may be inherited, caused by a drug reaction, reaction to a virus, environmental factors, or idiopathic

  30. ENOUGH KNOWLEDGE FOR ONE DAY