what is a type 1 hypersensitivity reaction?
Type I: Immediate Hypersensitivity (Anaphylactic Reaction) These allergic reactions are systemic or localized, as in allergic dermatitis (e.g., hives, wheal and erythema reactions). The reaction is the result of an antigen cross-linking with membrane-bound IgE antibody of a mast cell or basophil.