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44 Cards in this Set
- Front
- Back
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What are the 4 types of hypersensitivity reactions?
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ACID
I: Anaphylactic and Atopic II: Cytotoxic (antibody mediated) III: Immune complex IV: Delayed (cell mediated) |
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What happens in a type I hypersensitivty reaction?
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free antigen cross-links IgE present on mast cells and basophils that causes a release vasoactive amines (histamine) that act on postcapillary venules - reaction happens immediately after exposure because of the preformed antibody
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What types of hypersensitivity reactions are antibody mediated?
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Types I,II and III
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What are some examples of a type I hypersensitivity reaction?
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anaphylaxis: bee sting, some food/drug allergies
allergic/atopic: rhinitis, hay fever, eczema, hives, and asthma |
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What is the test to test for a type I hypersensitivity reaction?
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scratch test and radioimmunosorbent assay
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What happens in a type II hypersensitivity reaction?
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it is antibody mediated: IgM or IgG bind to fixed antigen on "enemy" cells (really a self cell), leading to lysis (by complement) or phagocytosis
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What are the 3 mechanisms of type II hypersensitivity reaction?
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1. Opsonize cells or activate complement
2. Antibodies recruit neutrophils and macrophages that incite tissue damage 3. Bind to normal cellular receptors and interfere with functioning |
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What is the test used for type II hypersensitivity reactions?
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direct and indirect Coombs test
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In what type of hypersensitivty does the disease tend to be specific to tissue or site where antigen is found?
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type II hypersensitivity reaction
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What are some examples of a type III hypersensitivity reaction?
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Hemolytic anemia, pernicious anemia, ITP, erythroblastosis fetalis, actue hemolytic transfusion reactions, rheumatic fever, goodpastures syndrome, bullous pemphigoid, pemphigus vulgaris, graves disease, myasthenia gravis
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How does a type III hypersensitivity reaction work?
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Immune complex, serum sickness, arthus reaction
Immune complex: antigen-antibody complexes activate complement which attracts PMN's, which release lysosomal enzymes Serum sickness: antibodies to foreign proteins are produced (takes 5 days). Immune complexes form and are deposited in membranes where they fix complement (leads to tissue damage). More common than arthus reaction Arthus reaction: local subacute antibody mediated hypersensitivty. Intradermal injection of antigen induces antibodies which form antigen-antibody complexes in the skin. Characterized by edema, necrosis, and activation of complement |
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What causes most serum sickness now?
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drugs (not serum from horses). See fever, urticaria, arthralgias, proteinuria, lymphadenopathy 5-10 days after antigen exposure.
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What test do you use to test for type III hypersensitivity?
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immunofluorescent staining
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What are examples of type III hypersensitivity reactions?
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SLE, RA, Polyarteritis nodosa, poststreptococcal glomerulonephritis, serum sickness, arthus reaction (swelling and inflammation following tetanus reaction), hypersensitivity pneumonitis (farmer's lung)
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How does type IV hypersensitivity reaction happen?
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Delayed (T-cell mediated): sensitized T lymphocytes encounter antigen and then release lymphokines (leads to macrophage activation; no antibody involved)
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What describes a type IV hypersensitivity reaction?
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4 T's
T lymphocytes, Transplant rejections, TB skin tests, Touching (contact dermititis) |
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How do you test for a type IV hypersensitivity reaction?
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patch test (PPD)
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What are some examples of a type IV hypersensitivity reaction?
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Type 1 DM, MS, Guillain-barre syndrome, hasimoto's thyroiditis, graft vs. host disease, PPD, contact dermatitis (for poison ivy and nickel allergy)
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What things are stuck together in an immune complex?
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antibody-antigen-complement
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bee sting
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type I hypersensitivity
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hives and asthma
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type I HS
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hemolytic anemia and pernicious anemia
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type II HS
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ITP
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type II HS
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Erythroblastosis fetalis
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type II HS
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acute hemolytic transfusion reactions
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type II HS
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rheumatic fever
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type II HS
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Goodpasture's syndrome
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type II HS
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bullous pemphigoid and pemphigus vulgaris
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type II HS
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graves disease
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type II HS
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myasthenia gravis
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type II HS
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SLE
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type III HS
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RA
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type III HS
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Polyarteritis nodosa
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type III HS
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poststreptococcal glomerlunoephritis
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type III HS
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serum sickness
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type III HS
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arthus reaction
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type III HS
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hypersensitivity pneumonititis
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type III HS
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type 1 DM
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type IV HS
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MS
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type IV HS
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Guillain Barre syndrome
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type IV HS
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hashimoto's thyroditis
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type IV HS
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Graft vs. Host
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type IV HS
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PPD
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type IV HS
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Contact dermatitis
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type IV HS
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