What is a macrophage found in the lung called?

• A. Alveolar cells
• B. Microglia
• C. Kupffer cells
• D. Osteoclasts

Answer: (A)

In the lung, the resident macrophage is called an alveolar macrophage. These cells reside in the alveolar spaces and are responsible for phagocytosing inhaled particles, pathogens, and debris to keep the air sacs clean for gas exchange. They originate from circulating monocytes and play a key role in innate immunity by releasing cytokines and reactive species when needed. The term alveolar cells, by contrast, refers to the alveolar epithelial cells lining the air spaces, not macrophages. Other organs have their own specialized macrophages—microglia in the brain, Kupffer cells in the liver, and osteoclasts in bone—so the lung-specific macrophage name best fits the question.