Allergy Introduction & Overview - OmniMedicalSearch.com

Conditions & Diseases: Lung & Respiratory Diseases & Disorders

Bronchitis

Introduction & Overview:

Allergies and other type of immune hypersensitivities are an important but undesirable side effect of our immune system. These problems occur in people who have a specific allergic tendency. Over 50 million fellow Americans or one in 6 suffer from allergies. Fortunately, very few people experience life threatening allergic conditions. In most allergy sufferers, problems appear to be trivial such as runny nose, sneezing, itchy eyes, sinus problem, rash and skin complaints but these otherwise minor problems can make the allergy sufferers lives quite miserable.

Our immune system, essential for defending our bodies against foreign organisms, produces antibodies and activated white cells to attack invaders like viruses and bacteria. Occasionally, this immune response results in an inappropriate or exaggerated reaction called hypersensitivity.

Hypersensitivity is classified into four types; Types I, II, III and IV. Types I to Type III hypersensitivities are antibody-mediated while Type IV is a cell mediated hypersensitivity. Type II & III are Immunoglobulin G (IgG) mediated while Type I sensitivity is Immunoglobulin E mediated. The term ‘Allergy’ is confined to IgE mediated reactions or Type I hypersensitivity [Levinson, 2004] .

Immunoglobulin E (IgE) is our body’s host defense system against certain parasites such as worms. In developed countries, where parasitic infection is uncommon, most people have no or very low level of IgE. An allergic reaction or allergy occurs when our body’s immune system mistakenly considers a harmless substance, called ‘allergen’ as dangerous and starts producing IgE to trigger an allergic reaction [Levinson, 2004].