Defining an Allergen
An allergen is any typically harmless substance that triggers an exaggerated immune response, known as an allergic reaction, in sensitive individuals. The body's immune system mistakenly identifies these substances as threats, leading to various symptoms. Allergens are most commonly proteins, but can also be other types of molecules.
How Allergic Reactions Occur
When a sensitized person encounters an allergen, their immune system produces specific antibodies called Immunoglobulin E (IgE). These IgE antibodies attach to mast cells, which are immune cells located in tissues throughout the body. Upon subsequent exposure to the same allergen, it binds to the IgE on the mast cells, prompting them to release inflammatory chemicals like histamine.
Common Examples of Allergens
Allergens are widespread and can originate from various sources. Frequently encountered allergens include airborne particles like pollen from trees, grasses, and weeds; microscopic dust mites; animal dander (skin flakes and dried saliva); certain food proteins found in peanuts, milk, eggs, or shellfish; insect venom from stings; and specific medications such as penicillin.
Impact and Management
Allergic reactions can manifest with a wide range of symptoms, from mild discomforts such as sneezing, itching, and skin rashes to severe, life-threatening conditions like anaphylaxis, which involves widespread swelling, breathing difficulties, and a rapid drop in blood pressure. Effective management often involves identifying and avoiding known allergens, alongside treatments like antihistamines, corticosteroids, or targeted immunotherapy.