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HYPERSENSITIVITY, Educational Platform.pptx
- 2. HYPERSENSITIVITY Imran Yousafzai BSN(Pak), MSPH(Pak),PGHRHM(UK), MHPE(Pak)
- 3. Objectives At the completionof this session learners would be able to: • review the following concepts of immune response – Components of immune response – Humoral versus cell mediated immunity – Antigen processing ,presentation and recognition • discuss the disorder of immune response i.e. Hypersensitivity ( allergies) – Immediate and delayed hypersensitivity • discuss the pathophysiology of different types of hypersensitivity (Type I, Type II, Type III & Type IV)
- 4. Hypersensivity What do youknow about hypersensitivity?
- 5. Immunity • Immunity isthe body's ability to fight off harmful microorganisms (Pathogens) that invade it. • The immune system produces antibodies or cells that can deactivate pathogens. • Fungi, protozoans, bacteria, and viruses are all potential pathogens.
- 6. Types of immunity •There are three types of immunity 1) Innate immunity 2) Active immunity 3) Passive immunity
- 7. Innate immunity: • Itis inborn or natural immunity. One may inherit some form of immunity from his or her mother milk. This is the innate immunity. • For example resistance of skin to the invasion by bacteria, destruction of germs in the stomach by its acidic secretion & enzymes and phagocytosis of bacteria and other invaders by WBCs.
- 8. Active Immunity • ActiveImmunity occurs when one makes his/her own antibodies. This type of immunity is long term. It has two subtypes – Naturally-Acquired Active Immunity: If you get an infectious disease (like VARICELLA), often times, that stimulates the production of MEMORY cells which are then stored to prevent the infection in the future. – Artificially-Acquired Active Immunity: Injecting or taking antigens by mouth. Takes time for T and B cells to be activated but gives long lasting immunity.
- 9. Passive Immunity • PassiveImmunity occurs when the antibodies come from some other source. This type of immunity is short term. • It has further divided in to two types. – Natural passive: Mother to child through placenta or milk. – Artificial passive: Used during potentially fatal diseases. Provides an instant response but only temporary as antibodies are not the body's own so memory cells are not created. E.g. tetanus - injection of antitoxins given.
- 10. Hypersensitivity refers toundesirable (damaging, discomfort-producing and sometimes fatal) reactions produced by the normal immune system. OR ‘over reaction’ of the immune system to harmless environmental antigens
- 11. Types of hypersensitivity reactions TypeI: immediate hypersensitivity Type II: cytotoxic hypersensitivity Type III: Immune complex –type hypersensitivity Type IV: cell mediated hypersensitivity or Delayed-type hypersensitivity
- 12. Type I hypersensitivity(allergy) • Occur and disappear rapidly • The major problem is functional disorder almost without tissue injury • Prerequisite: need prior sensitization to antigen • Mediated by Ig E antibody • Bear an individual difference: atopic families are susceptible to allergic disease • Rapid liberation of active chemicals such as histamine and serotonin
- 13. Triggers • Food –peanuts • Insects – bee sting • Drugs/Chemicals – penicillin • Animal Dander – cat • Dust – mites • Plant Pollen • Mold Spores – penicillium
- 14. The major componentsand cells participating in Type I hypersensitivity 1. Allergens 2. Allergins: IgE 3. Mast cells and basophil 4. Eosinophil
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- 16. Mechanism of typeI hypersensitivity 1. Allergy-induced period 2. allergy-stimulated period 3. effector period
- 17. Allergy-induced period Allergen Production ofIg E IgE binds to mast cells and basophils
- 18. Tissue Affected The tissuesmost commonly affected are the skin, the respiratory tract and the alimentary tract. The results are at best uncomfortable (e.g. hay fever, eczema, food allergy) at worst fatal (asthma, anaphylaxis)
- 19. Comparison of normalbronchiole to asthmatic bronchiole
- 20. • Symptoms ofsystemic anaphylactic
- 21. Type II • TypeII hypersensitivity is also known as cytotoxic hypersensitivity and may affect a variety of organs and tissues.
- 22. Type 2 Hypersensitivityreaction • In this condition IgG or IgM antibodies are formed which react with surface proteins of the bodies own cells. The result in complement-mediated lysis of the cells • Examples: • Hemolytic disease of the new born (Rhesus disease) where lgG antibodies transferred from the mother lyse the babies cells • Rare, but serious, are cases where drugs or their metabolites bind to red cell or platelet membranes and induce antibody formation. This is found as a sporadic reaction with a range of drugs
- 23. Examples:Type II • Drug-inducedhemolytic anemia, granulocytopeniaDrug-induced hemolytic anemia, granulocytopenia and thrombocytopenia are such examples. The reaction time is minutes to hours. • Hemolytic disease of the new born (Rhesus disease) where lgG antibodies transferred from the mother lyse the babies cells
- 24. Hemolytic disease ofthe new born 1st Pregnancy is normal Subsequent Pregnancy baby
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- 26. Type III Hypersensitivity •Type III hypersensitivity is also known as immune complex hypersensitivity (IgG & IgM). • The reaction may be general (e.g., serum sickness) or may involve individual organs including skin (e.g., systemic lupus erythematosus), joints (e.g., rheumatoid arthritis) or other organs.
- 27. Type IV Hypersensitivity •Type IV hypersensitivity is also known as cell mediated or delayed type hypersensitivity. • The classical example of this hypersensitivity is tuberculin (Montoux) reaction which peaks 48 hours after the injection of antigen (PPD or old tuberculin). • The lesion is characterized by indurationThe lesion is characterized by induration and erythema.
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