Allergy

People has different reactions to some substances, and an adverse reaction can be allergy - such as reaction to polen, insect bites, allergy to some types of food, and cosmetics, etc.

What is allergy
Allergy is a defensive immune response to some substances when the body does not recognize those. The purpose of this reaction is to inactivate this foreign substance and to protect against a potential harm to the body.

Mechanism

Allergy is a hypersensitivity reaction that needs an initial exposure to the substance that causes allergy (allergen). The allergen next stimulates specialized cells (lymphocites) to produce antibody (IgE) that is specific for this allergen. The IgE is released and attached to the surface of another specialized group of cells called mast cells, present in various tissues in the body.

The next time the person is exposed to the allergen, they will specifically attach to the IgE on the surface of the mast cells and prompt these cells to release chemicals, such as histamine. Histamine will cause some of the allergy symptoms - that's why medications for allergy include anti-histamine.

Extreme Allergy cases
Allergic reaction can be life-threatening. Mast cells activation, specially when the allergen is injected - injectable drugs and insects bites - can cause a potentially fatal syndrome called anaphylactic shock. Symptoms include 1. increase in vascular permeability causing a dramatic drop on the blood pressure; 2. airways constrict, causing difficulty in breathing; and 3. swelling of the epiglottis that can cause suffocation in susceptible individuals. The timely injection of epinephrine relaxes the smooth muscle and reverses the scenario.

Anything can be an allergen responsible to trigger allergies – food, cosmetics additives, preservatives, fragrances and other substances. In case of an initial reaction, probe what might have caused the reaction and avoid products that contain such substances.

Happy Holidays and a Healthy 2008!

Vanessa