. "C3116"^^ . "Immediate Hypersensitivity"^^ . "Immediate hypersensitivity reaction - type I reaction, involves immunoglobulin E (IgE)-mediated release of chemical mediators from mast cells and basophils. Th2 cells produce IL-4 and IL-13, which then act on B cells to promote the production of antigen-specific IgE. Reexposure to the antigen can then result in the antigen binding to and cross-linking the bound IgE antibodies on the mast cells and basophils. This causes the release of preformed mediators (histamine, tryptase, tryptase, chemotactic factors), newly synthesized mediators (leukotrienes, prostaglandin, thromboxane, platelet-activating factor, adenosine, bradykinin), and cytokines from these cells that results in structural and functional changes to the affected tissue.NCI" . "Hypersensitivity reactions which occur within minutes of exposure to challenging antigen due to the release of histamine which follows the antigen-antibody reaction and causes smooth muscle contraction and increased vascular permeability.MSH2003_2003_05_12" . "Immediate Hypersensitivity"^^ . . "Immediate HypersensitivityPTNCI" . "C0020523"^^ . "Immediate_Hypersensitivity"^^ . "Disease or Syndrome"^^ . .