Allergen is defined as which of the following?

Allergen is defined as which of the following?

• A. Substance causing allergic reaction
• B. Substance triggering immune response
• C. Severe systemic infection
• D. Immediate hypersensitivity reaction

Answer: (A)

An allergen is the substance that prompts an allergic reaction in someone who is sensitized. In many allergies, exposure leads to IgE antibodies binding the allergen, mast cells degranulating, and release of histamine and other mediators that produce symptoms. The allergen is the trigger for this exaggerated immune response, not just any immune activation. It’s not a severe systemic infection, which is an infectious disease, nor is it the reaction itself (an immediate hypersensitivity reaction is the process, while the allergen is what starts it).

An allergen is the substance that prompts an allergic reaction in someone who is sensitized. In many allergies, exposure leads to IgE antibodies binding the allergen, mast cells degranulating, and release of histamine and other mediators that produce symptoms. The allergen is the trigger for this exaggerated immune response, not just any immune activation. It’s not a severe systemic infection, which is an infectious disease, nor is it the reaction itself (an immediate hypersensitivity reaction is the process, while the allergen is what starts it).