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20 Cards in this Set
- Front
- Back
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Hypersensitivity is
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inappropriate immune response that causes pathology. ex is urticaria (an edema response)
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Allergy is
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an inappropriate immune response after exposure to an otherwise innocuous exogenous agent. it's from T cell involvement.
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What is the body's first response to an allergen?
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nada. no sneeze, no runny nose. no pathogenic response. APC eats up the allergen and presents it to MHC Class II.
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The TH2 has to be in a certain environment, what does it have to be in the presence of?
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IL-4 (systemic) and IL-13 (local) produced by TH2 T cells. These IL's will then cause isotype switching in a B-cell to produce IgE
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What is the default response in a baby?
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Type II. You have to learn the Type I off the Type II.
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What does IgE bind to?
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Binds high affinity FcERI
(mast cells, basophils, and eosinophils). IgE sits there and waits to see the Ag again. If it sees the allergen again, it tells the mast cell to release its granules *does not fix complement **does not cross placenta |
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What is the wheal? What is the flare?
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Wheal is the raised part from edema. Usually blanched white.
Flare- the red part surrounding. Due to vasodilation. |
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Early and Late Phase Responses
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Immediate phase- within 15 minutes. Big drop in FEV1. Upper airway constriction and mast cell degranulation. histamine release and edema. Mast cell-mediated
Late phase- transcription factors release the inflammatory mediators. Eosinophil-mediated |
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Allergic Rhinitis
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Most common Type I hypersensitivity (immediate and late phase)
IgE-mediated and localized to the nasal mucosa and conjunctiva Swollen nasal mucosa with watery secretions! Mad eosinophils in nasal secretions and tissues. Perennial or seasonal. "Hay fever" AVOIDANCE- main pt management |
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Anaphylaxis
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Systemic response
IgE mediated Must have previously encountered the antigen!! sudden drop in BP; hypovolemic shock Histamine Feeling jittery, fright, Penicillin!! can be any type of hypersensitivity. Tx with epinephrine |
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Type II Hypersensitivity
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"Cytotoxic"
-IgG and IgM mediated -attached to a cell -examples are ADCC and complement mediated cell lysis -common reactions are Blood transfusion, hemolytic disease or newborn, autoimmune hemolytic anemia |
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Type II hypersensitivity Autoimmune Diseases
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-Goodpasture's Syndrome
-Pemphigus -Myasthenia gravis -Type I diabetes |
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Direct and Indirect Coomb's Test
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Direct- Tells if you have antibodies on the surface of your cells. Positive in all hemolytic type II disorders
Indirect- if the Abs floating around COULD be against somebody else's cells |
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Type III
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"Immune Complex"
-the Ag that the Abs are made against are soluble in the blood and lymph, so it moves around -antibody-antigen complexed formed that can't be removed easily (need equal amounts of both to form the complex) |
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what is the shot glass test looking for?
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Petichiae of antibody-antigen. stopped in capillary bed because it's too big to go through, so it stays in the endothelial cells, then causes leakage. These are non-blanchable.
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Type III Hypersenstivity contained within the blood vessels?
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Within- Causes Serum Sickness; mad dangerous; increases vascular permeability and endothelial leakage
Outside- Arthus Reaction; get a very long first exposure instead of first and second exposure |
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Diagnostically differentiate Type II and Type III Hypersensitivities
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Smooth tissue and can see what looks like tissue-specific staining is Type II (Ab directly against the tissue)
Granular, punctate appearance is a Type III (complexes are deposited there) |
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Type IV Hypersensitivity
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"Delayed"
-anything NOT antibody mediated! -Antigens activate T-cells and cause a cellular hypersensitivity response -activation of CD8+ cells instead of CD4+ cells -ex. contact dermatitis, poison ivy |
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weird thing about type IV hypersensitivity
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even after the sensitization phase, if you encounter the allergen again, you still have to process the antigen and activate the T cell again, and that takes 24-48 hours. You don't have T-cells hanging around the skin. The T-cell doesn't recognize free antigen.
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What are granulomas
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If the body can't get rid of something or beat it up, it forms a wall around it. T-cells stimulate the macrophages, which stimulate fibroblasts in the connective tissue. On the interior you have macrophages and giant cells. necrotic center in older granulomas.
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