Experimental assessment of bronchopulmonary responses to inhaled materials should commence with an analysis of the integrated function of the several defense mechanisms of the lung. The use of radioactive tracer-labelled bacterial aerosols delivered in a quantitative airborne fashion provides an overall evaluation of the hazard of inhaled materials to bronchopulmonary phagocytic activity and clearance. The method permits the division of experimental efforts early in the course of investigation into those that should be directed toward the pathophysiology of transport mechanisms, particularly the mucociliary stream, and those that should be directed toward the pathophysiology of phagocytic mechanisms at deeper levels of the lung. This division early in the experimental program gives justification to more intensive efforts to pursue pathogenic agents in in vitro systems.
Green GM. Integrated Defense Mechanisms in Models of Chronic Pulmonary Disease. Arch Intern Med. 1970;126(3):500-503. doi:10.1001/archinte.1970.00310090130017