Pathogenesis of Chronic Urticaria: An Overview

Table 4

Mast cell mediators: relevant to chronic urticaria.

Mediator	Effect in chronic urticaria
Preformed mediators
Histamine	Direct potent vasoactive and smooth muscle spasmogenic effects; Principal mediator of vascular changes [70, 71]
Newly synthesised mediators
Lipid mediators
LTC4; LT B4; PGD2	Actions similar to histamine; Potentiate vasodilatation, vascular permeability, and smooth muscle contraction; Chemotactic for neutrophils and eosinophils [72]
Cytokines and chemokines
Tumour necrosis factor-alpha	Newly synthesised as well as preformed
	Upregulates expression of adhesion molecules on endothelial cells; Promotes leukocyte rolling and adhesion; Chemotactic for neutrophils [73]
Interleukin-1	Proinflammatory cytokine; Lymphocyte activator [74]; Activates mast cells after release from leukocyte [75]
Interleukin-4	Chemotactic for neutrophils; Recruits eosinophils [76]
Interleukin-5	Recruits eosinophils [77]
Interleukin-6	Proinflammatory cytokine; Activates lymphocytes [78]
Interleukin-8/CXCL2	Member of C X C chemokines; Potent neutrophil chemoattractant; Involved in neutrophil degranulation, respiratory burst, and adhesion to endothelial cells [79]
MCP-1/CCL2	Chemoattractant for eosinophils
MIP-1 alpha/CCL3	Chemoattractant for eosinophils
Interleukin-16	Chemoattractant for T-lymphocytes
RANTES/CCL5	Chemoattractant for eosinophils [79]

LTC4: leukotriene C4, LTB4: leukotriene B4, PGD2: prostaglandin D2, MCP-1: monocyte chemotactic protein-1, MIP-1 alpha: monocyte inflammatory peptide-1, RANTES: regulated upon activation normal T-cell expressed and secreted.