Which white blood cell type is commonly elevated in allergic reactions?

• A. Eosinophils
• B. Neutrophils
• C. Lymphocytes
• D. Monocytes

Answer: (A)

Allergic reactions trigger a Th2-driven response that promotes eosinophil involvement. Eosinophils are produced in greater numbers when IL-5 signals the bone marrow to release them and chemokines guide them into inflamed tissues. Once present, they release toxic proteins that contribute to the late-phase inflammation characteristic of allergies, making them a common and prominent finding in allergic processes such as allergic rhinitis, asthma, and atopic dermatitis. Other white blood cells tend to rise for different reasons: neutrophils for bacterial infections, lymphocytes for viral infections or certain chronic immune responses, and monocytes for chronic inflammation or some infections. This pattern helps explain why eosinophils are the most typical elevation in allergic reactions.