Histamine in anaphylaxis is secreted by

Ans. a (Mast cells). (Ref. Robbins pathology, 8th ed., Table 2-4; 2-6).Mediators of anaphylaxis are many--histamine, serotonin, PGS, VIP, Leukotrienes, TxA2, etc., hut histamine is produced and secreted by mast cells.The Actions of the Principal Mediators of InflammationMediatorSourcePrincipal ActionsCell-DerivedHistamineMast cells, basophils, plateletsVasodilation, increased vascular permeability, endothelial activationSerotoninPlateletsVasodilation, increased vascular permeabilityProstaglandinsMast cells, leukocytesVasodilation, pain, feverLeukotrienesMast cells, leukocytesIncreased vascular permeability, chemotaxis, leukocyte adhesion and activationPlatelet-activating factorLeukocytes, endothelial cellsVasodilation, increased vascular permeability, leukocyte adhesion, chemotaxis, degranulation, oxidative burstReactive oxygen speciesLeukocytesKilling of microbes, tissue damageNitric oxideEndothelium, macrophagesVascular smooth muscle relaxation; killing of microbesCytokines (e.g. TNF, IL-1)Macrophages, lymphocytes, endothelial cells, mast cellsLocal endothelial activation (expression of adhesion molecules), systemic acute-phase response; in severe infections, septic shockChemokineLeukocytes, activated macrophagesChemotaxis, leukocyte activationPlasma Protein-DerivedComplementPlasma (produced in liver)Leukocyte chemotaxis and activation, opsonization, vasodilation (mast cell stimulation)KininsPlasma (produced in liver)Increased vascular permeability, smooth muscle contraction, vasodilation, pain