What type of white blood cells are involved in allergen response and protection against parasites?

Eosinophils play a crucial role in the body's response to allergens and in defending against parasitic infections. These specialized white blood cells are characterized by their unique granules that contain enzymes and proteins capable of combating larger pathogens, such as helminths (worms). When the body encounters allergens, eosinophils are recruited to the site of exposure, where they release substances that help mediate inflammation and tissue response. Their levels often rise significantly during allergic reactions and parasitic infections, which underscores their importance in these immune processes.

In contrast, neutrophils primarily act in the acute inflammatory response and are more involved in fighting bacterial infections. Lymphocytes, while vital for immune responses, particularly in viral infections and adaptive immunity, do not predominantly target allergens or parasites directly like eosinophils do. Monocytes are precursors to macrophages and are involved in the phagocytosis of pathogens and cell debris but are not specifically linked to allergic reactions or parasitic defense. Thus, eosinophils are specifically recognized for their dual role in both allergy and parasitic diseases, making them the correct answer to the question.