Vol. 1, Issue 3 (2012)

Author(s):
Debjit bhowmik, K. P. Sampath Kumar*, M. Umadevi

Abstract:
An allergic reaction is the body's way of responding to an "invader." When the body senses a foreign substance, called an antigen, the immune system is triggered. The immune system normally protects the body from harmful agents such as bacteria and toxins. Its overreaction to a harmless substance (an allergen) is called a hypersensitivity reaction, or an allergic reaction. Allergy involves an exaggerated response of the immune system. The immune system is the body's organized defense mechanism against foreign invaders, particularly infections. Allergens are substances that are foreign to the body and can cause an allergic reaction. IgE is the allergy antibody. Allergies can develop at any age. Your risk of developing allergies is related to your parents' allergy history. Allergies are your body’s reaction to a substance it views as a harmful ‘invader.’ For example, coming into contact with what is normally a harmless substance, such as pollen, might cause the immune system (the body’s defense system) to react. Substances that cause these reactions are called allergens. An "allergic reaction" is way the body responds to the allergen. A chain of events occur that result in an allergic reaction, described here. The first time an allergy-prone person is exposed to a specific allergen (such as pollen), the body responds by producing allergic (IgE) antibodies. The job of these antibodies is to find molecules of the offending substance in the bloodstream and tissues and to escort them to the body’s mast cells (a type of white blood cell) for destruction. As the mast cells destroy the allergens, a chemical called histamine is released into the bloodstream. A large amount of histamine swells body tissues (inflammation), causes itching, enlarges blood vessels, increases secretions, and causes bronchospasm.