I M M U N O LO GY
9
Allergies and What We Need to Know About Them by Sharrada Subramaniam
H
ow often do you suffer from an annoying runny nose, sneezing, watery eyes, or hives on your skin? The common cold shares many similar symptoms; however, what goes unnoticed very often is the underlying allergy. An allergy is a disorder of the immune system whereby the body overreacts to the allergen (substance causing the allergy). An allergen could be an airborne particle (e.g., house dust mites or pollen), a food allergen (commonly peanuts, milk or seafood), and other proteins such as natural rubber latex, animal dander, toxins from insect stings or drugs (e.g., penicillin or aspirin). An allergic response can range anywhere from being mild and hardly noticeable, to dangerous and life threatening. Common allergic symptoms include sneezing, watery eyes and itching, while severe allergic responses can lead to breathing difficulties (asthma) due to narrowing of the airways or excess mucus production. The most severe, often life threatening, form of an allergy is anaphylaxis, which leads to a systemic response affecting major body systems. Worldwide statistics from the American Academy of Allergy, Asthma, and Immunology (AAAAI) show that up to 40% of the world population is sensitised to foreign antigens, while 10-30% of the population amounting to hundreds of millions of people are affected by allergic rhinitis [1,2]. Three hundred million others suffer from asthma [1]. For the last 50 years, the prevalence of allergies has shown an increasing trend [1]. Risk factors and causes In Malaysia, we are frequently exposed to dust mites, pollen, and spores. While many of us are immune to these harmless allergens, they trigger an allergic reaction in others. It is not fully understood why some people respond to the allergens, but not others, although genetics and environmental factors may play a role. The genetic predisposition to have an allergic disease is 70% if an identical twin has it, and 40% for nonidentical twins [3]. Early contact with airborne allergens could cause atopic disease later in life [4].
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Atopy is a condition whereby individuals are more likely to develop an allergic response to allergens. Atopic individuals have a higher level of serum immunoglobulin E (IgE) antibody compared to healthy people. Genetic studies have identified candidate genes and gene cluster patterns that might explain these differences. Some allergies are present from a young age while others can develop over time. Overexposure to an allergen for a prolonged period of time can lead to a process of sensitisation to the allergen. Children who grow up being near to cats and dogs whose dander is a common cause of allergies are at a higher risk of ISSUE 9 / NOVEMBER 2014
