Allergin

Allergin is a term sometimes used to describe a substance capable of triggering an allergic reaction in susceptible individuals. In current practice, the more common word is allergen, but allergin appears in older literature and in discussions of hypothetical or newly identified substances. For the purposes of this article, an allergin is any molecule, particle, or complex that can evoke an IgE-mediated immune response and produce symptoms ranging from itching and sneezing to life-threatening anaphylaxis.

The immune process typically starts with sensitization, during which exposure to the allergin leads to production of specific IgE antibodies. These antibodies bind to mast cells and basophils. On later exposures, the allergin cross-links the bound IgE, triggering release of histamine and other mediators and causing symptoms such as wheeze, hives, nasal congestion, or stomach upset.

Common sources of allergins include plant pollens, food proteins (such as peanuts, milk, or shellfish), insect venoms, certain medications, metals, and chemicals used in cosmetics or industrial settings. The potency and the route of exposure (skin contact, inhalation, ingestion, or injection) influence whether an allergin will provoke a clinical reaction in a given person.

Diagnosis relies on medical history, skin prick testing, and serum tests for allergen-specific antibodies. Management emphasizes avoidance of the allergin when possible, rapid access to emergency care, and medications such as antihistamines, nasal or inhaled corticosteroids, and, for severe reactions, epinephrine. Immunotherapy or desensitization may be considered for some allergens under medical supervision.

Research on allergins continues to identify new potential allergens, improve diagnostic tests, and develop safer immunotherapies.