Atopy Describes the clinical features of individuals who develop Type I hypersensitivity increased vascular permeability ·local edema 。itching Strong hereditary linkages Mediated by a serum factor termed "reagin" "Wheal and flare"reaction Atopy ◼ Describes the clinical features of individuals who develop Type I hypersensitivity ◼ increased vascular permeability ◼ local edema ◼ itching ◼ Strong hereditary linkages ◼ Mediated by a serum factor termed "reagin" ◼ "Wheal and flare" reaction