What Causes Allergies?
WHAT CAUSES ALLERGIES?
The allergic response involves a complex network of immune system cells and their chemical factors. When an allergen (an otherwise harmless substance that causes allergic reactions in some susceptible individuals) comes in contact with allergic antibody (IgE) coating mast cells, these cells immediately release histamine and other chemical factors. Histamine binds to histamine receptors found on cells lining the respiratory passages, gastrointestinal tract and blood vessels. The action of histamine binding to histamine receptors may cause a variety of allergic symptoms, including runny nose, sneezing and congestion (“hay fever” or allergic rhinitis which can lead to sinusitis); cough and wheezing (asthma); allergic rashes (hives and eczema); and even severe, life-threatening reactions to foods, medications and insect stings (anaphylaxis).
Approximately 15-20% of the population has some form of allergy. Although the tendency to have allergic reactions often runs in families, this tendency does not necessarily apply to specific allergies. For example, a woman who wheezes with exposure to cats and a man who is allergic to peanuts may have a child who develops allergy to ragweed pollen (“hay fever”). In general, a person’s risk of developing allergic sensitivities increases to 30-40% if one parent or sibling has allergies and rises to 60-80% if two or more members of the immediate family have allergies.