What is an allergy?An allergy is the response of the body's immune system to a normally harmless substance, such as animal hairs, pollen, food, or house dust mite. The body has an automatic reaction to what it sees as a threat, and while in most people these substances pose no problem, in those with allergies the immune system identifies them as a threat and produces an inappropriate response to them. Allergies are classified into IgE mediated and non-IgE mediated allergies. In IgE mediated allergies the immune system then begins to produce begins to produce a class of antibodies known as IgE, specific for that particular allergen, which will later alert the fighting cells (mast cells and basophils) within the immune system every time that this substance is encountered.
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