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Diseases Hypersensitivity- Types

Diseases Hypersensitivity- Types. Types of Type 1 hypersensitivity. Type I Reactions Can Be Systemic Localized. SYSTEMIC ANAPHYLAXIS. occurs within minutes after the allergen is introduced in blood (bee sting or through gut)

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Diseases Hypersensitivity- Types

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  1. Diseases Hypersensitivity- Types

  2. Types of Type 1 hypersensitivity • Type I Reactions Can Be • Systemic • Localized

  3. SYSTEMIC ANAPHYLAXIS • occurs within minutes after the allergen is introduced in blood (bee sting or through gut) • Symptoms range from mild urticaria (hives) to shock-like symptom i.e. • anaphylaxis may become fatal e.g. • respiration may become labored • blood pressure may drop • Airway constriction • Swelling of epigottis • Difficulty in breathing • Usually against foods such as peanuts or bee sting

  4. Some historians claim that Egypt's first pharaoh, Menes, was killed by a wasp's sting

  5. Treatment • Epinephrine is the drug of choice for systemic anaphylactic reactions: • relaxing the smooth muscles and reducing vascular permeability • improves cardiac output

  6. SYSTEMIC ANAPHYLAXIS • Urticaria may be: • Acute (type I) • chronic (type II) • Might be caused by: • venom from bee, wasp, hornet, and ant stings; • drugs, such as penicillin, insulin, and antitoxins; • seafood and nuts • If not treated quickly, these reactions can be fatal

  7. Interestingly Some IgE mediated anaphylaxis in response to insect venom, drugs or foods are not associated with atopy

  8. LOCALIZED ANAPHYLAXIS (ATOPY) • Tendency to manifest localized anaphylactic reactions is inherited and is called atopy • In localized anaphylaxis, the reaction is limited to aspecific target tissue or organ- epithelial surfaces at the site of allergen entry • Atopic allergies, which afflict at least 20% of the population in developed countries • include a wide range of IgE-mediated disorders • including allergic rhinitis (hay fever), • asthma, • Atopic dermatitis (eczema) • and food allergies

  9. Late-Phase Reactions Induce LocalizedInflammatory Reactions • As a type I hypersensitive reaction begins to subside, mediators released during the course of the reaction often induce localized inflammation called the late-phase reaction • The late-phase reaction begins to develop 4–6 h after the initial type I reaction and persists for 1–2 days • The reaction is characterized by infiltration ofneutrophils, eosinophils, macrophages, lymphocytes, and basophils • The localized late-phase response also may be mediated partly by cytokines released from mast cells

  10. Mediators of early and late phase responses of Type 1 hypersensitivity

  11. Allergy- Treatments

  12. Avoid contact . Removal of house pets, dust-control measures, or avoidance of offending foods . Elimination of inhalant allergens –pollens is a physical impossibility Type I Hypersensitivities Can BeControlled Medically • to avoid contact with known allergens • Often the removal of house pets, • dust-control measures, • or avoidance of offending foods can eliminate a type I response

  13. Immunotherapy • the use of humanized monoclonal anti-IgE • repeated injections of increasing doses of allergens (hyposensitization) has been known for some time to reduce the severity of type I reactions • shift toward IgG production • to induce T-cell– mediated suppression

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