title: Mast cell mediators other than histamine induce pruritus in atopic dermatitis patients: a dermal microdialysis study.
abstract: While histamine is the crucial mediator of pruritus in type 1 allergic reactions, its role in atopic dermatitis (AD) is unclear. In this study, the role of mast cell mediators in protein extravasation and pruritus was evaluated using intradermal microdialysis. The microdialysis capillaries were used to apply the mast cell degranulating substance compound 48/80 (C48/80; 0.05%) or histamine (0.01%) and also to deliver H1-blockers (cetirizine, 200 microg mL-1) in nine AD patients and nine controls. Large pore size membranes (3000 kDa) enabled simultaneous analysis of protein extravasation. Itch sensation was measured psychophysically and weal and flare reaction were evaluated planimetrically. Protein extravasation induced by histamine and C48/80 was significantly reduced in AD patients. Blockade of H1-receptors by cetirizine significantly reduced C48/80-induced protein extravasation in AD patients and controls to an identical level. C48/80-induced pruritus was abolished by cetirizine in controls, whereas pruritus in AD patients was unchanged after H1 blockade. We conclude that mast cell mediators others than histamine are involved in C48/80-induced pruritus in AD patients. Whether the reduced capacity of AD patients to induce protein extravasation is of pathophysiological relevance for pruritus remains to be established.
authors.affiliation: Department of Physiology and Experimental Pathophysiology, University of Erlangen/Nürnberg, Universitätsstr. 17, D-91054 Erlangen, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Rukwied
authors.forename: G
authors.initials: G
authors.lastname: Lischetzki
authors.forename: F
authors.initials: F
authors.lastname: McGlone
authors.forename: G
authors.initials: G
authors.lastname: Heyer
authors.forename: M
authors.initials: M
authors.lastname: Schmelz
mesh_terms: D000328:Adult; D017332:Cetirizine / Q000627:therapeutic use; D003876:Dermatitis, Atopic / Q000150:complications* / Q000378:metabolism; D005260:Female; D006632:Histamine / Q000502:physiology; D006634:Histamine H1 Antagonists / Q000627:therapeutic use; D006801:Humans; D018836:Inflammation Mediators / Q000009:adverse effects / Q000502:physiology*; D008297:Male; D008407:Mast Cells / Q000378:metabolism*; D017551:Microdialysis; D011506:Proteins / Q000378:metabolism; D011537:Pruritus / Q000139:chemically induced* / Q000188:drug therapy / Q000209:etiology
chemical_list: D006634:Histamine H1 Antagonists; D018836:Inflammation Mediators; D011506:Proteins; D006632:Histamine; D017332:Cetirizine