ABSTRACT
Alveolar macrophages are a major portion of the immune protection of the lung. Whether the lung is attacked by virus, bacteria, fungi, parasites, or such foreign particles as silica, coal dust, or asbestos, alveolar macrophages are activated to kill or clear the unwanted foreign material. They act as a kind of vacuum cleaner and executioner of foreign matter in the lung so that oxygen exchange can occur in the small sacks known as alveoli. Oxygen diffuses through the alveolar walls into the blood and into the erythrocytes, which carry exchangeable oxygen to the tissues. The macrophages patrol the internal surface of the lung and keep it clean of foreign substances so that the lung can do its job and oxygenate the blood efficiently.
