Immediate hypersensitivity

{
  "id": "MLC-T-ENV-013830",
  "term": "Immediate hypersensitivity",
  "field": "Environment",
  "term_source": "Immediate Hypersensitivity",
  "definition": "1. 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.\n\n2. 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.",
  "subject": "Biological substances",
  "references": [
    "National Cancer Institute Thesaurus"
  ],
  "url": "https://mlchart.com/terminology/environment/immediate-hypersensitivity/"
}