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Imm:Hypersensitivity
Hypersensitivity Reactions
Question | Answer |
---|---|
Anaphylaxis | Type I |
Allergic rhinitis (hay fever) | Type I |
Asthma | Type I |
Eczema | Type I |
IgE mediated: free Ag cross-links IgE on presensitized mast cells and basophils --> trigger release of vasoactive amines | Type I |
Ab mediated: IgM, IgG bind fixed Ag on cell--> lysis by complement or phagocytosis | Type II |
Immune complex mediated: Ag-Ab complex activates complement --> attract neutrophils --> neutrophils release lysosomal enzymes | Type III |
Delayed (T-cell) mediated: sensitized T lymphocytes encounter Ag --> release lymphokines --> macrophage activation | Type IV |
Contact dermatitis | Type IV |
Allergic rhinitis & anaphylaxis | Type I |
Hemolytic anemia | Type II |
Idiopathic thrombocytopenic purpura | Type II |
Erythroblastosis fetalis | Type II |
Rheumatic fever | Type II |
Goodpasture's syndrome | Type II |
Bullous pemphigoid | Type II |
Graves' disease | Type II |
Myasthenia gravis | Type II |
SLE | Type III (immune complex) |
Rheumatoid arthritis | Type III (immune complex) |
Polyarteritis nodosum | Type III |
Post-strep glomerulonephritis | Type III |
Serum sickness | Type III (immune complex) |
Arthus reaction | Type III |
Hypersensitivity pneumonitis | Type III (immune complex) |
Type I diabetes mellitus | Type IV |
Multiple sclerosis | Type IV |
Guillain-Barre syndrome | Type IV |
Hashimoto thyroiditis | Type IV |
Graft vs host disease | Type IV |
PPD (TB test) | Type IV |
Contact dermatitis | Type IV |
Type II (Ab-mediated) | IgM, IgG bind to Ag on "enemy" cell-->lysis or phagocytosis |
Type III (immune complex) | Ag-Ab complexes activate complement which attract PMNs who release dangerous substances |
Type IV (delayed) | Sensitized T cells encounter Ag and release lymphokines to activate macrophages |
Type III (serum sickness) | Fever, urticaria, arthralgias, proteinuria, lymphadenopathy 5-10 days after Ag exposure |