Allergies and How They Work

Causes of Allergies

Allergies are defined as bodily overreactions (allergic reactions) that occur when the immune system is exposed to harmful substances (allergens). Examples of common allergens include protein rich foods such as peanuts and eggs, fragrances, insect stings, pollen and dust mites. While each of these allergens produces unique symptoms, the most common ones include hives, watery eyes, a running nose, breathing problems and at times, death.

How the Immune System Works in Fighting Allergens

Our immune system, which is made up of several cells and organs, is designed to work both independently and jointly, with the intent of fighting all kinds of pathogens. But despite it being highly efficient and active, it’s not perfect. It’s common for the immune system to mistake a harmless substance as being harmful. Whenever this happens, the immune system attacks this substance (allergen) as though it’s harmful hence, resulting to an allergic reaction.

The Breakdown of Allergic Reactions

The_Allergy_Pathway

Whatever happens at the time(s) of an allergic reaction is referred to as an allergic cascade or allergic chain of events. So an allergic chain of events starts when an allergen enters the body and white blood cells (the B cells and the T cells), which are responsible for identifying and eradicating pathogens, misidentifies it by assuming that it’s harmful. This prompts the body to start producing Immunoglobulin E antibodies (IgE) which consist of engineered proteins set to neutralize the threat posed by the allergen. Thus, in preparation for another invasion by the same allergen, the IgE antibodies attach themselves on a mast cell, which is a specialized blood cell  found on our gastrointestinal (GI) tract and airways.

Therefore, when the body is exposed to the same allergen for the second time, IgE antibodies start breaking down the mast cell. Once the cell’s walls have been broken down, various chemicals (leukotrienes, prostaglandins and histamine) are released into the blood stream and the surrounding tissues. These chemicals then combine with various blood receptors and body tissues hence leading to a number of allergic symptoms such as hives, sneezing, a running nose and swelling, among others. Histamine is however the most active chemical for once it has mixed with blood receptors and body tissues; it starts causing symptoms that end up affecting the cardiovascular and respiratory system as well the gastrointestinal tract and the skin.

Essentially, if the allergen has been ingested, then, one is likely to get their intestines, stomach or mouth affected. If it is airborne, then, one is bound to develop symptoms on their lungs, nose or eyes. This will probably lead one to have problems breathing or may have watery eyes or a runny nose. However, if one is exposed to the allergen through their skin, then they are bound to experience some form of itchiness, develop a rash or have the area swell.

Correlation Between Allergies and Genetics

Even though one cannot inherit an allergy from their parent(s), the tendency of developing an allergy is inheritable. For instance, if you are allergic to eggs, chances are that your child will also have an allergy, but towards a different allergen.

The chances of your offspring inheriting this tendency are approximated at 33%. But in the case where both parents have allergies, then the tendency is increased to 65-75%.

N.B:

The term atopic is used to refer to someone who is susceptible to allergies.
According to medical studies, atopic individuals are more susceptible to asthma than non-atopic individuals.

Resource: 

http://en.wikipedia.org/wiki/List_of_allergens

http://www.webmd.com/allergies/guide/chronic-allergies-causes

http://www.medicinenet.com/allergy/page2.htm

http://acaai.org/allergies/symptoms

http://www.emedicinehealth.com/allergic_reaction/article_em.htm

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