Immunity notes

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Immunity notes

  1. 1. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 1 Hypersensitivity  Altered immunologic response to an antigen that results in disease or damage to the host
  2. 2. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 2 Hypersensitivity (cont’d)  Allergy  Deleterious effects of hypersensitivity to environmental (exogenous) antigens  Autoimmunity  Disturbance in the immunologic tolerance of self-antigens  Alloimmunity  Immune reaction to tissues of another individual
  3. 3. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 3 Hypersensitivity (cont’d)  Characterized by the immune mechanism:  Type I • IgE mediated  Type II • Tissue-specific reactions  Type III • Immune complex mediated  Type IV • Cell mediated
  4. 4. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 4 Hypersensitivity (cont’d)  Immediate hypersensitivity reactions  Anaphylaxis  Delayed hypersensitivity reactions
  5. 5. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 5 Type I Hypersensitivity  IgE mediated  Against environmental antigens (allergens)  IgE binds to Fc receptors on surface of mast cells (cytotropic antibody) - “sensitized”  Histamine release  H1 and H2 receptors  Antihistamines
  6. 6. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 6 Type I Hypersensitivity (cont’d)  Manifestations:  Itching  Urticaria  Conjunctivitis  Rhinitis  Hypotension  Bronchospasm  Dysrhythmias  GI cramps and malabsorption
  7. 7. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 7 Type I Hypersensitivity (cont’d)  Genetic predisposition- atopic  Tests:  Food challenges  Skin tests  Laboratory tests  Desensitization  Cautiously
  8. 8. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 8 Type I Hypersensitivity (cont’d)
  9. 9. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 9 Type II Hypersensitivity  Tissue specific  Specific cell or tissue (tissue-specific antigens) is the target of an immune response
  10. 10. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 10 Type II Hypersensitivity (cont’d)  Five mechanisms:  Cell is destroyed by antibodies and complement  Cell destruction through phagocytosis  Soluble antigen may enter the circulation and deposit on tissues; tissues destroyed by complement and neutrophil granules  Antibody-dependent cell-mediated cytotoxicity (ADCC)  Causes target cell malfunction (e.g., Graves)
  11. 11. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 11 Type III Hypersensitivity  Immune complex mediated  Antigen-antibody complexes are formed in the circulation and are later deposited in vessel walls or extravascular tissues  Not organ specific  Serum sickness  Raynaud phenomena  Arthrus
  12. 12. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 12 Type IV Hypersensitivity  Does not involve antibody  Cytotoxic T lymphocytes or lymphokine producing Th1 cells  Direct killing by Tc or recruitment of phagocytic cells by Th1 cells  Examples:  Acute graft rejection  Skin test for TB  Contact allergic reactions  Some autoimmune diseases
  13. 13. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 13 Allergy  Most common hypersensitivity and usually type I  Environmental antigens that cause atypical immunologic responses in genetically predisposed individuals  Pollens, molds and fungi, foods, animals, etc.  Often allergen is contained within a particle too large to be phagocytosed or is protected by a nonallergenic coat  Bee stings
  14. 14. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 14 Autoimmunity  Breakdown of tolerance  Body recognizes self-antigens as foreign  Self-antigens not normally seen by the immune system  Infectious disease (e.g., rheumatic fever, glomerulonephritis)  Antigenic mimicry  Neoantigen  Haptens become immunogenic when they bind to host proteins
  15. 15. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 15 Autoimmune Examples  Systemic lupus erythematosus (SLE)  Chronic multisystem inflammatory disease  Autoantibodies against: • Nucleic acids • Erythrocytes • Coagulation proteins • Phospholipids • Lymphocytes • Platelets, etc.
  16. 16. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 16 Autoimmune Examples (cont’d)  Systemic lupus erythematosus (SLE)  Deposition of circulating immune complexes containing antibody against host DNA  More common in females
  17. 17. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 17 Systemic Lupus Erythematosus  Clinical manifestations:  Arthralgias or arthritis (90% of individuals)  Vasculitis and rash (70%-80%)  Renal disease (40%-50%)  Hematologic changes (50%)  Cardiovascular disease (30%-50%)
  18. 18. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 18 Systemic Lupus Erythematosus (cont’d)  Eleven common findings:  Serial or simultaneous presence of at least four indicates SLE
  19. 19. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 19 Alloimmunity  Immune system reacts with antigens on the tissue of other genetically dissimilar members of the same species  Transplant rejection and transfusion reactions: • Major histocompatibility complex (MHC) • Human leukocyte antigens (HLC)  Transfusion reactions • ABO blood groups  Rh incompatibility • Hemolytic disease of newborn
  20. 20. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 20 Graft Rejection  Transplant rejection is classified according to time  Hyperacute • Immediate and rare • Preexisting antibody to the antigens of the graft  Acute • Cell-mediated immune response against unmatched HLA antigens
  21. 21. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 21 Graft Rejection (cont’d)  Transplant rejection is classified according to time  Chronic • Months or years • Inflammatory damage to endothelial cells of vessels as a result of a weak cell-mediated reaction against minor HLA antigens
  22. 22. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 22 Graft-Versus-Host Disease (GVHD)  Immunocompromised individuals are at risk for CVHD  T cells in the graft are mature and capable of cell-mediated destruction tissues within the recipient  Not a problem if patient is immunocompetent

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