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Dr. Eduardo G Gonzales

What causes allergy? Why are some people allergic to certain things while others are not? How can you prevent allergies? – Miguel P., San Fernando City

Allergy is a disorder that involves the immune system – the body’s strongest defense against invading microorganisms and harmful foreign substances.

This system is run by cells called lymphocytes. In the presence of an antigen or material that is foreign to the body, some lymphocytes transform into plasma cells, which then produce a substance called antibody or immunoglobulin that is capable of destroying the antigen.

The immune system is vital to the survival of the individual but it can go awry. Sometimes, as in the case of a number of autoimmune diseases such as systemic lupus erythematosus (SLE) or rheumatoid arthritis, it fails to distinguish self from non-self such that its agents attack the body’s own tissues and cells. At other times, as in the case of allergy or allergic reaction, it reacts inappropriately and often, overwhelmingly, to what usually is a harmless substance.

Any substance that can trigger an allergy is called an allergen. Allergens come in a variety of forms – pollen, excreta of house dust mites, animal dander, molds, cockroaches, drugs, certain foods, etc. An allergen can trigger an allergic reaction by getting in contact with the skin or the mucous membrane of the eyes, or by getting inhaled, ingested, or injected.

Why a particular substance can elicit an allergy in some people and not in others is unknown, but it is almost certain that allergy has a genetic basis. In fact, a family history of allergy is the most important predisposing factor for the disease.

As a rule, a person does not develop an allergic reaction the first time he/she encounters an allergen. The initial exposure merely sensitizes the person to the allergen and produces no symptoms.
During the first encounter with an allergen, the person’s lymphocytes, in response to the allergen, produce antibodies called immunoglobulin E (IgE) that are specific for the particular allergen. After they are formed, these antibodies attach themselves on the surface of two very similar cells, basophils and mast cells, where they wait for another meeting with their particular allergen. Basophils are a type of white blood cells while mast cells are a type of connective tissue cells that are particularly numerous in the eyes, and the respiratory and gastrointestinal tracts.

During the next and subsequent times the person encounters the allergen to which he/she has been sensitized, the IgEs capture the allergen and this prompts the basophils and mast cells (to which the IgEs are attached) to release the chemicals that they contain.

These chemicals are responsible for the inflammation, swelling and other signs and symptoms of allergy. They also attract other cells such as eosinophils (another type of white blood cell) that add more inflammatory chemicals.

The signs and symptoms of allergy are usually mild – sneezing, itchy and runny nose, watery eyes, itchiness of the skin and skin rashes including hives. Sometimes, an allergy can trigger an asthmatic attack.

Rarely, an allergy comes in the form of an anaphylactic shock, a severe and life-threatening form of allergic reaction that is characterized by sudden swelling and constriction of the airways and widening of blood vessels causing a drop in blood pressure.

Many people know their allergens. Those who do not can often identify theirs by undergoing a skin prick or other tests for allergens. Knowing one’s allergens is important because the best way to prevent an allergic attack is by avoiding the allergens to which one is sensitive to.

There are several types of drugs that are currently employed to relieve the signs and symptoms of allergy. Of these, the antihistamines are the most commonly used. Other important drugs include cromolyn and corticosteroids.

These drugs however, should not be used without the supervision of a physician.
In cases where the allergen can not be avoided, allergen immunotherapy is sometimes employed to desensitize a person to a particular allergen.

This treatment is performed by an immunologist (a physician who specializes in allergies and related diseases) and consists of injecting tiny amounts of the allergen under the skin over a period of time. Allergen immunotherapy is however not always effective, although in many instances, the allergic attacks are reduced in number and severity, if not outright prevented.

Address inquiries on health matters to Dr. Eduardo G. Gonzales, DLSU College of Medicine, Dasmariñas, Cavite 4114.


tnx doc!

me tanong ako, kelangan ba ng nurses sa osaka iridology?


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