Which leukocyte is agranulocyte, largest in size, and functions in phagocytosis?

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

Answer: (C)

Monocytes are the agranulocytes that are largest in size and actively perform phagocytosis. They circulate as large, non-granulated white blood cells and, when they migrate into tissues, differentiate into macrophages. Macrophages swallow and digest microbes, dead cells, and debris, and they also present antigens to help drive the immune response. Neutrophils are granulocytes and are smaller phagocytes that respond quickly to infection but don’t fit the “agranulocyte” criterion. Lymphocytes are also agranulocytes but are smaller and specialize in adaptive immunity rather than primary phagocytosis. Eosinophils are granulocytes involved in parasitic infections and allergies, not the largest cells. So, the cell that matches all parts of the description is the monocyte.