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MUA M2B2 IDR 04
Hypersensitivity
Term | Definition |
---|---|
Hay fever is an example of | type 1 HS, Mediated by IgE, basophils and mast cells |
Hemolytic anemia is and example of | type 2 HS with IgG and IgM, PMNs Macrophages, and NK cells |
Graves disease, Myasthenia gravis and type 2 diabetes are examples of | type 2 HS with IgG and no immune cell mediators |
Arthus reaction and Rheumatoid Arthritis are examples of | type 3 HS with IgG and IgM |
Type 1 diabetes and Hashimotos are examples of | type 4 HS with no Ig and Cytotoxic T cells, Th1s and macrophages |
an immunogen that induces an allergic response. (10- 40 kD; diffusible, soluble, and stable), have peptides that bind to host MHC Class II molecules | Allergen |
Individuals with high blood IgE and high eosinophils | Atopic people |
Type 1 severe symptoms are caused by | allergen crosslinking with IgE, binding to FceRI on mast cells |
Normal individuals | do not mount strong TH2 responses to most foreign antigens |
IL-4 and IL-13, secreted by TH2 cells | stimulate B lymphocytes to switch to IgE-producing cells. |
Histamine | causes the dilatation of blood vessel, increases vascular permeability; & stimulates the contraction of smooth muscles |
Proteases | causes damage to local tissues |
Leukotrienes | Smooth muscle contraction, increase vascular permeability, and mucus secretion. (similar to histamine, but in the later stages) |
PAF | chemotactic for leukocytes, and activation of neutrophil, eosinophil, and platelet |
Platelet Activating Factor | increased vascular permeability, vasodilation; also, adhesion of PMNs to endothelial cells (recruitment) |
Prostaglandins | vasodilation, edema; made by cyclo-oxygenases (COX enzymes) |
Prostaglandins are inhibited by | NSAIDS |
IL-3, IL-5, GM-CSF | promote eosinophil production and activation |
TNF-a | promotes inflammation, stimulate cytokine production |
Lipid mediators | Leukotirenes and PAF |
Cause Vascular leak, Bronchoconstriction, Intestine hypermotility | Histamines, PAF, PGD2, LCT4 |
Cause inflammation | TNF, PAF PGD2, LCT4 |
Cause tissue damage | tryptase |
Immediate type 1 HS reaction | Histamine |
Cause late phase type 1 HS reaction | cytokines, chemokines, leukotrienes from mast cells leads to neutrophil and eosinophil chemotaxis |
IL5 | is released by TH2 cells and stimulate bone marrow growth and basophil production |
In basophils IgE binds to | FceR1 |
A cluster of genes on chromosome 5 includes the genes all directly involved in isotype switching, eosinophil survival, and mast-cell proliferation | IL-4, IL-3, IL-5, IL-9, IL-12, IL-13, and GM-CSF. |
Uticaria: localized raised itchy swelling in the skin | |
Characteristic of allergic rhinitis, bronchial asthma | late phase response in HS 1 The acute responses in allergic asthma leads to TH2 mediated chronic inflammation. |
Atopic Dermatitis (Eczema) | prolonged allergic response with chronic and itching skin rash with associated skin eruptions and fluid discharge. frequently presents in families with a history of asthma and allergic rhinitis, and is often associated with high IgE levels |
Histamine caused GI symptoms | stimulates gastric acid secretion and smooth muscle contraction. manifest periorally or as vomiting or diarrhea |
The Rast Test (Radioallergosorbent Test) Detects | Allergen-specific IgE In Serum -many false positives and negatives |
. small quantities of common allergens is injected into the skin and look for the characteristic response | Skin Test: primary method for diagnosing type 1 HSR being a “wheal and flare” reaction |
Anaphylaxis | (shock) caused by vascular dilatation; airway obstruction due to laryngeal edema. starts with itching (oral, or hives), then constriction of bronchioles and respiratory distress, followed by vomiting, diarrhea, cramps, laryngeal obstruction, and death. |
Desensitization | repeated administration of small doses of allergens. Idea is to change the T cell response away from TH2 dominant ANERGY. skews the response towards IgG or from the humoral to cellular one. |
How is desensitation regulated | Induction of T regulatory cells secreting IL-10 and TGF-b |
Successful desensitazion treatments | are associated with the production of allergen-specific antibodies of the IgG4 isotype and increased levels of IL-10. |
Common treatments for type 1 HS | avoidance, pharmalogical impact reduction, desensitazion |