Definition: An induced systemic or generalized sensitivity; at times the term anaphylaxis is used for anaphylactic shock. The term is commonly used to denote the clinical reaction seen with system IgE-mediated hypersensitivity reaction. Multivalent antigen crosslinks IgE on the surface of tissues mast cells, causing degranulation with release of preformed mediators (histamine). Generation of newly synthesized mediators occurs rapidly. The physiologic manifestations reflect the biologic effects of these mediators. Cutaneous symptoms include pruritus, erythema, urticaria, and angioedema. Respiratory compromise can come from laryngeal obstruction or bronchospasm. Cardiac effects include arrhythmia, hypotension, and shock. The reaction may be fatal if asphyxiation or cardiovascular collapse occurs.
Synonym(s): anaphylactic reaction
[G. ana, away from, back from, + phylaxis, protection]
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