Phagocytes include all of the following, except:

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

Answer: (A)

Phagocytosis is the process of engulfing and digesting invading organisms or debris by specialized white blood cells. Neutrophils are classic quick-responding phagocytes that actively ingest bacteria. Monocytes circulate in the blood and differentiate into macrophages in tissues, and these macrophages are long-lived phagocytes that clear pathogens and debris. Macrophages also help present ingested material to other immune cells, linking innate and adaptive responses. Lymphocytes, including B cells, T cells, and natural killer cells, are primarily involved in adaptive immunity and cytotoxic functions rather than engulfing pathogens, so they are not considered phagocytes. Therefore, the element that does not fit with the others as a phagocyte is the lymphocytes.