Leukocytes elevated in parasitic infections and allergic reactions?

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

Answer: (B)

Eosinophils are the white blood cells most closely linked to fighting parasitic infections and mediating allergic reactions. In parasitic infections, especially helminths, eosinophils accumulate and release cytotoxic granules that help damage or kill the parasites. In allergic reactions, they respond to IgE-mediated signals and contribute to inflammation through degranulation and release of inflammatory mediators. Because of these roles, eosinophil counts rise specifically in parasitic and allergic conditions, making them the best answer. Neutrophils rise mainly with bacterial infections and acute inflammation, lymphocytes with viral or certain chronic immune responses, and monocytes with chronic inflammation and macrophage activity—patterns that aren’t as closely tied to parasites and allergies.