Which white blood cell is used to destroy parasites?

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

Answer: (B)

Parasites, especially multicellular ones like helminths, are most effectively attacked by eosinophils. These granulocytes are drawn to parasitic sites and recognize parasites coated with IgE through their Fc receptors. When activated, they release cytotoxic granules containing major basic protein, eosinophil cationic protein, and other oxidants that damage the parasite’s surface and help kill it. Eosinophils also participate in antibody-dependent cellular cytotoxicity, linking the antibody response to direct parasite destruction.

B lymphocytes mainly produce antibodies rather than directly destroying parasites, though antibodies can help recruit other cells. Basophils play a larger role in allergy and releasing histamine, not parasite destruction. Neutrophils are excellent at phagocytosing bacteria and fungi but are not the primary effector against parasites.