The effect of alveolar macrophage chemotaxis on bacterial clearance from the lung surface.

In the distal airways, the alveolar macrophage plays a crucial role in defense of the lung against inhaled pathogens. These cells have been observed in vitro to move chemotactically in response to many types of attractants that may be present on the lung's surface during a bacterial or particulate challenge. This study investigated the hypothesis that chemotactic ability is an important part of the defensive action of these cells as they ingest bacteria on the lung surface. We compared our mathematical model for lung clearance to previously published bacterial clearance data and determined the amount of alveolar macrophage chemotactic ability required to account for observed clearance rates. The results showed that random motion is insufficient for clearance, and a moderate amount of chemotactic ability is necessary for our predicted clearance rates to agree with experimentally measured clearance rates.