Which cells are phagocytic?

Which cells are phagocytic?

• A. Granulocytes
• B. Lymphocytes
• C. Macrophages and lymphocytes
• D. Neutrophils and macrophages

Answer: (D)

Phagocytosis is the process by which certain immune cells ingest and destroy invading microbes and debris. The cells that do this most effectively are neutrophils and macrophages. Neutrophils race to sites of infection and rapidly engulf bacteria, using toxic enzymes and reactive oxygen species to kill them. Macrophages are larger, longer-lived phagocytes that reside in tissues or circulate as part of the monocyte pool; they also ingest pathogens and dead cells and play a key role in alerting other parts of the immune system by presenting antigens. Understanding why the other options aren’t as accurate helps reinforce the concept. Granulocytes include neutrophils, eosinophils, and basophils; while neutrophils are phagocytic, eosinophils and basophils are not the primary phagocytes, so describing all granulocytes as phagocytic isn’t correct. Lymphocytes (B cells, T cells, and NK cells) are mainly involved in specific immune responses rather than ingestion of pathogens, so they aren’t chiefly phagocytic. Therefore, the best pairing is neutrophils and macrophages.

Phagocytosis is the process by which certain immune cells ingest and destroy invading microbes and debris. The cells that do this most effectively are neutrophils and macrophages. Neutrophils race to sites of infection and rapidly engulf bacteria, using toxic enzymes and reactive oxygen species to kill them. Macrophages are larger, longer-lived phagocytes that reside in tissues or circulate as part of the monocyte pool; they also ingest pathogens and dead cells and play a key role in alerting other parts of the immune system by presenting antigens.

Understanding why the other options aren’t as accurate helps reinforce the concept. Granulocytes include neutrophils, eosinophils, and basophils; while neutrophils are phagocytic, eosinophils and basophils are not the primary phagocytes, so describing all granulocytes as phagocytic isn’t correct. Lymphocytes (B cells, T cells, and NK cells) are mainly involved in specific immune responses rather than ingestion of pathogens, so they aren’t chiefly phagocytic. Therefore, the best pairing is neutrophils and macrophages.