Lecture 18: Hypersensitivity Reactions Flashcards Preview

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Flashcards in Lecture 18: Hypersensitivity Reactions Deck (31):
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Type I hypersensitvity is mediated by

IgE and results from the actions of mediators secreted by the mast cells 

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Type II hypersensitvity is mediated by 

Abs that bind tissue Ags and cause complement-dependent tissue injury and disease

3

Type III hypersensitivity is mediated by 

Abs that bind to circulating Ags to form immune complexes, which deposit in vessels and cause complement-dependent injury in the vessel wall (vasulitis) 

4

Type IV hypersensitivity is mediated by 

T cells and results from inflammation caused by cytokines produced by CD4+ Th1 and Th17 cells, or killing of host cells by CD8+ CTLs

5

____ refers to the genetic tendency to develop allergic diseases. 

Atopy (individuals with a strong propensity to develop allergic reactions are said to be atopic) 

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The Seqeunce of events in the development of immediate hypersensitivity reactions

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difference between immediate and late phase of Type I hypersensitivity

  • The immediate vascular and smooth muscle reaction to allergen develops within minutes
    • Morphology of the immediate reaction is characterized by
      • vasodilation
      • congestion
      • edema
  • The late-phase reaction develops 2-24 hours later
    • characterized by:
      • inflammatory infiltrate rich eosinophils, neutrophils, and T cells 

8

Characteristics of asthma and bronchospasms 

  • Local reaction
  • Inflammatory mediators cause the loosening of tight junctions in the bronchiole epithelium, increased capillary permeability, and spasmatic contraction of smooth muscle surrounding bronchi
    • this temporarily decreases the size fo the bronchial lumen, resulting in shortness of breath 

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Anaphylaxis

  • Systemic reaction
  • exposure to allergen may cause the rapid release of vasoactive amines from mast cells and basophils as well as a flood of cytokines, resulting in the contraction of smooth muscle in the vasculature and vasodilation of capillary endothelium 
  • blood pressure decreases, resulting in vascular shock
  • in addition, the release of mediators increases the contraction of smooth muscles in the bronchi and bronchioles of the respiratory tract, making breathing difficult

10

alleren testing assess Type ____ hypersensitivities to various potential allergens

Type I hypersensitivities  (positive reactions are indicated as redness and swelling within 20 to 30 minutes after exposure to the allergen) 

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Effector mechanisms of Type II hypersensitivity 

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Diseases of Type II Hypersensitivity 

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Diseases of Type III hypersensitivity

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Diseases of Type IV Hypersensitivity

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Tissue injury from Type IV hypersensitivity (delayed-type Hypersensitivity (DTH))

  • Tissue injury results from the products of the recruited and activated neutrophils and macrophages, such as lysosomal enzymes, reactive oxygen species, nitric oxide, and proinflammatory cytokines 

16

Granulomas contain 

  • activated macrophages, multinucleated giant cells, and lymphocytes (primarily T cells)
  • (caused by TB escaping the macrophage and causing it to go crazy)

17

Function of leukotrienes

Stimulate prolonged smooth muscle dilation 

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The classical T cell-mediated inflammatory reaction is called _______

delayed-type hypersensitivity (DTH) 

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In a delayed-type hypersensitivity (DTH) reaction what are the makure cells that secrete cytokines and recuruite/activate leukocytes

Th1 and Th17

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23

Contact dermatitis is an example of what type of hypersensitivity

Type IV (delayed hypersensitivity) 

24

Formation of a mature granuloma

  • Within hours to days after Ag exposure, Activated Th1 cells home ot the tissue
  • If the source of Ags is not eradicated, inflammation will persist
  • Th1 Cd4+ T cells and activated Macrophages by IFN-gamma which leads to production of TNF
  • IFN-gamma and TNF further stimulate macrophages
  • Over the course of several days to weeks a mature granuloma is formed 

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Principles of immunotherapy

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What is the principle diagnostic test for systemic lupus erythrematosus

Anti-nuclear Abs

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