What are allergens?

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Multiple Choice

What are allergens?

Allergens are antigens that set off allergic reactions. They’re usually foreign proteins or glycoproteins that the immune system recognizes as threats. In people who are susceptible, exposure to an allergen prompts the production of IgE antibodies that coat mast cells and basophils. When the same allergen is encountered again, it cross-links the IgE on these cells, triggering degranulation and release of histamine and other mediators. That cascade produces the typical allergy symptoms, such as itching, sneezing, swelling, or bronchoconstriction. Not all antigens cause allergy—only those that provoke this IgE-mediated response. The liver doesn’t generate allergy-mediating substances, and antibodies aren’t the trigger themselves; they are part of the response that occurs after the allergen is recognized.

Allergens are antigens that set off allergic reactions. They’re usually foreign proteins or glycoproteins that the immune system recognizes as threats. In people who are susceptible, exposure to an allergen prompts the production of IgE antibodies that coat mast cells and basophils. When the same allergen is encountered again, it cross-links the IgE on these cells, triggering degranulation and release of histamine and other mediators. That cascade produces the typical allergy symptoms, such as itching, sneezing, swelling, or bronchoconstriction. Not all antigens cause allergy—only those that provoke this IgE-mediated response. The liver doesn’t generate allergy-mediating substances, and antibodies aren’t the trigger themselves; they are part of the response that occurs after the allergen is recognized.

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