ANATOMY

Detailed explanation-1: -Allergies are one of the most common chronic diseases. An allergy occurs when the body’s immune system sees a substance as harmful and overreacts to it. The substances that cause allergic reactions are allergens.

Detailed explanation-2: -Any substance which is recognized by the immune system is an antigen. In the case of people with allergies, the allergens are picked up by certain cells, called antigen-presenting cells, which process them and allow them to be recognized by and to alert the innate immune system to their presence.

Detailed explanation-3: -If you have an allergy, your immune system overreacts to an allergen by producing antibodies called Immunoglobulin E (IgE). These antibodies travel to cells that release chemicals, causing an allergic reaction.

Detailed explanation-4: -In technical terms, an allergen is an antigen that is capable of stimulating a type-I hypersensitivity reaction in atopic individuals through immunoglobulin E (IgE) responses. Most humans mount significant Immunoglobulin E responses only as a defense against parasitic infections.