Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 89. Chapters: Toxicodendron radicans, Allergy, Aerobiology, Pollen, Anaphylaxis, Allergen, Gluten sensitivity, Food intolerance, Food allergy, Major urinary proteins, Allergen immunotherapy, International Study of Asthma and Allergies in Childhood, Hygiene hypothesis, Wheat allergy, Elimination diet, Hypoallergenic dog breed, Peanut allergy, Oat sensitivity, Ragweed, Allergic rhinitis, Egg allergy, Oral allergy syndrome, Helminthic therapy, Sublingual immunotherapy, Aeroallergen, Antigen leukocyte cellular antibody test, Pool chlorine hypothesis, Stallergenes, MELISA, List of allergies, Milk allergy, Skin allergy test, Latex allergy, Aspirin-induced asthma, Cat allergy, Hay fever in Japan, Soy allergy, Allergic inflammation, Tree nut allergy, Hypersensitivity, Idiosyncrasy, Bet v I allergen, American College of Allergy, Asthma & Immunology, Aquagenic urticaria, Laboratory animal allergy, Exercise-induced anaphylaxis, Platinosis, Garlic allergy, Prausnitz-Kustner test, American Academy of Allergy, Asthma, and Immunology, Jan Lotvall, Cladosporium, FITkit, Seafood allergy, Insect sting allergy, Drug allergy, Citric acid intolerance, Skeeter syndrome, Pseudoanaphylaxis, Slow-reacting substance of anaphylaxis, Fruit allergy, Perfume allergy, Polish Society of Allergology, Pseudoallergy, Corn allergy, Betadexin, Duraphen, Can f 1. Excerpt: Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur to normally harmless environmental substances known as allergens; these reactions are acquired, predictable, and rapid. Strictly, allergy is one of four forms of hypersensitivity and is called type I (or immediate) hypersensitivity. It is characterized by excessive activation of certain white blood cells called mast cells and basophils by a type of antibody known as IgE, resulting in an extreme inflammatory respons...