Immunology xii allergy

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Immunology xii allergy

  1. 1. Hypersensitivity diseases
  2. 2. Downloaded from: StudentConsult (on 18 July 2006 11:40 AM) © 2005 Elsevier
  3. 3. Type-I Hypersensitivity
  4. 4. Basic terms <ul><li>Type-I = E arly= IgE-mediated = A topic = A naphylactic type of hypersensitivity </li></ul><ul><li>Atopy = genetic predisposition to type-I hypersensitivity diseases. It is a genetic predisposition to react by IgE production to various stimuli. </li></ul>
  5. 5. Frequency of atopic diseases <ul><li>20-30% of general population is estimated to be atopic . </li></ul><ul><li>Preva lence o f bronchial asthma: </li></ul><ul><ul><li>General po p u l ation 5-6% </li></ul></ul><ul><ul><li>Children: 10% </li></ul></ul><ul><li>Every year 100 people die in E u rope of anapylactic shock due to wasp/bee sting . </li></ul>
  6. 6. Genetic aspects of atopy <ul><li>Probability of atopy in a child : </li></ul><ul><ul><li>Both parents atopics: 80%, </li></ul></ul><ul><ul><li>One parent atopic: 50%, </li></ul></ul><ul><ul><li>No patent is atopic: 15%. </li></ul></ul><ul><li>Concordance of a s thma in monozygotic twins: only 50-69% </li></ul>
  7. 7. Candidate genes of atopic diseases <ul><li>5q31-33 : cytokines and their receptors : IL-4, IL-5, IL-9, IL-13 </li></ul><ul><li>11q13: high affinity receptor for IgE </li></ul><ul><li>6p: HLA genes. TNF-  </li></ul><ul><li>1q, 4q,7q31, 12q14.3-q24.31, 14q11.2-g13, 16p21, 17q, 19q </li></ul>
  8. 8. Common allergens <ul><li>Pollens (grass, trees) </li></ul><ul><li>House dust mites ( Dermatophagoides pteronyssimus and farinae ) </li></ul><ul><li>Foods: nuts, chocolate, shellfish, mil k , egg, fruits </li></ul><ul><li>P ets (cat, dog) </li></ul><ul><li>Moulds </li></ul>
  9. 9. Type-I hypersensitity
  10. 10. http://pathmicro.med.sc.edu/mayer/IgStruct2000.htm
  11. 11. Serum IgE levels in atopic dirseses
  12. 12. Regulation of IgE production <ul><li>Positive regulation: IL-4 a IL-13 – products of Th2 cells </li></ul><ul><li>Negative regulation: IFN  - product of Th1 cells </li></ul>
  13. 13. Regulation of production of Th1/Th2 cells
  14. 15. Mast cells
  15. 16. Activation of mast cells
  16. 17. Biological effects of histamin <ul><li>H1: Smooth muscle contraction, increased permeability of capillaries, vasodilatation, increased production of nasal and bronchial secretions, chemotaxis of leukocytes </li></ul><ul><li>H2: increase in gastric juice production, increased production of secretions on respiratory tract </li></ul><ul><li>H3: receptors present in CNS </li></ul>
  17. 18. Consequences of activation of mast cells
  18. 19. Downloaded from: StudentConsult (on 18 July 2006 11:40 AM) © 2005 Elsevier Consequences of activation of mast cells
  19. 20. Immediate and late phase of allergic reaction
  20. 21. Phases of type-I hypersensitivity reaction <ul><li>Immediate phase – clinical symptons evolve in several minutes. Mediated mainly by histamin. </li></ul><ul><li>Late phase – symptoms evolve after hours (6-8). Mediated mainly by leukotriens. Presence o f eosinophils plays an important role in allergic infl a mmation . </li></ul>
  21. 22. Allergic reaction in bronchi
  22. 23. Eozino ph il granulocyt e
  23. 24. Clinical diseases caused by atopic hypersenitivity <ul><li>Allergic conjunctivitis </li></ul><ul><li>Allergic rhinitis </li></ul><ul><li>Bronchial asthma </li></ul><ul><li>Allgergy of gastrointestinal tract </li></ul><ul><li>Urticaria and angioedema </li></ul><ul><li>Atopic eczema </li></ul><ul><li>Anaphylactic shock </li></ul>
  24. 25. Allergic conjunctivitis
  25. 26. Allergic rhinitis
  26. 28. Bronchial asthma
  27. 29. Urticaria
  28. 30. Angioedema
  29. 32. Atopic eczema
  30. 33. Atopic eczema
  31. 34. Atopic eczema
  32. 35. Treatment of allergic diseases <ul><li>Allergen avoidance </li></ul><ul><li>Antihistaminics </li></ul><ul><li>Cromons (cromolyn sodium, nedocromil) - stabilise membrane of the mast cells </li></ul><ul><li>Topical or systemic corticosteroids </li></ul><ul><li>Antilekotriens </li></ul><ul><li>In asthma:  -2 agonists, xantins </li></ul><ul><li>Allergen immunotherapy (desensitisation) </li></ul>
  33. 36. Diagnostic approaches in type-I hypersensitivity <ul><li>Past history </li></ul><ul><li>Eosinophilia </li></ul><ul><li>Skin tests </li></ul><ul><li>Provocation and elimination tests </li></ul>
  34. 37. Skin prick tests
  35. 39. Causes of anaphylactic shock <ul><li>Drugs - penicillins, cephalosporins, proteolytic enzymes, local anestetics </li></ul><ul><li>Foods - nuts, seafood, chocolate </li></ul><ul><li>Allergen desensitisation, allergen skin tests </li></ul><ul><li>Bee or wasp sting </li></ul><ul><li>X-ray contrast media </li></ul>
  36. 40. Clinical symptoms of anphylactic shock <ul><li>Hypotension (systolic pressure 90 mm Hg or less) </li></ul><ul><li>Tachykardia </li></ul><ul><li>Dyspnea </li></ul><ul><li>Abdominal pain, nausea </li></ul><ul><li>Anxiety </li></ul><ul><li>Urticaria on the skin, sweating, itching </li></ul><ul><li>Contractions of the uterus </li></ul>
  37. 41. Treatment of anaphylactic shock <ul><li>Adrenalin intravenously or intramusculary 10  g/kg repeatedly </li></ul><ul><li>Antihistaminics intravenously </li></ul><ul><li>Syntophyllin 240 mg intravenously or inhalation of  -2-mimetics </li></ul><ul><li>Corticosteroids ( 200-500 mg of hydrocortisone) intravenously </li></ul><ul><li>Oxygen </li></ul><ul><li>Vasopressor agents (dopamin or noradrenalin) </li></ul>
  38. 42. Type-II hypersensitivity
  39. 43. Anti-GBP antibodies 
  40. 44. Type-III hypersensitivity
  41. 45. Type III hpersensitivity
  42. 46. Skin vasculitis
  43. 47. Serum Sickness –Type III
  44. 48. Type IV hypersensitivity
  45. 50. Tuberculin reaction
  46. 51. Contact dermatitis due to nickel hypersensitivity
  47. 52. Contact dermatitis

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