National Geographic : 2006 May
Polollen Pollen protein - , Prostaglandins Leukotrienes Histamine @ 0 Release The symptoms of an allergic reaction are caused by a series of chemicals released from the mast cell. Some act right away, others gradually after the first response. First response Prostaglandins, leukotrienes, and histamine work on nerve endings to cause itching and inflammation of tissues; they act on glands to cause mucus production and vasodilation, so you clog up. Later response Cytokines and chemokines are cell-to-cell communicators. They recruit other cells that slowly increase tissue damage. Cytokines H, * B rF~ ^w 9 ^*^e ^ y®v Che okiesjif". w ^ ss~a.SS f S-% NGM ART Attacking a Harmless Intruder - E Enter Allergen particles-proteins from pollen, animal dander, or other substances that are normally harmless-penetrate the body by inhalation, ingestion, injection, or skin contact. -E Combine IgE antibodies, defenders in the immune system, attach to the surface of a mast cell and wait for subsequent contact with an allergen. Then allergen proteins bind with the IgE, alerting the mast cell to react to the intruder. gE antibody |- Trigger Mast cells, which help the body fight parasitic infections, overreact when allergens enter the picture, emitting waves of biochemical defense.