Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology
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The mediator mechanisms of the cutaneous wheal and flare response, which underlies allergic skin and urticarial conditions, are controversial. The wheal results primarily from a direct effect of histamine on the local vascular bed but to what extent does histamine diffuse within the wheal? The flare is neurogenic, in origin, being disseminated within the dermis by axon reflexes, but do the neuropeptides released from the nerve endings cause the vasodilatation directly or do they induce the further release of histamine which then transduces the flare? ⋯ These data support the theory that the flare reaction to focal histamine injection or release is a neurogenic reflex not involving histamine release at its effector end.