Which white blood cell is primarily involved in allergic responses by releasing histamine?

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

Answer: (B)

Allergic responses hinge on histamine release from cells packed with granules that release mediators when activated by IgE cross-linking. Basophils are circulating white blood cells that store histamine in their granules. When an allergen cross-links IgE bound to basophils, these cells degranulate and release histamine, which increases blood vessel permeability and causes symptoms like redness, swelling, and itchiness. The tissue-resident counterparts, mast cells, do a similar job, but this question focuses on circulating blood cells, making basophils the best match. Neutrophils are primarily bacterial first responders and don’t release histamine as a main function. Eosinophils participate in parasite defense and modulate allergic inflammation but aren’t the primary histamine-releasing cells. Lymphocytes are adaptive immune cells involved in specific immune responses rather than histamine release.