The kinetics of macrophage and surfactant replacement in hamster lung following bronchopulmonary lavage.

The effects of bronchopulmonary lavage with isotonic NaCl have been investigated in the hamster, and methods are described for separating pulmonary surfactant from cells in lavage fluid and for the quantitative isolation of surfactant from lung. It has been shown that hamsters almost invariably survived a lavage which consisted of ten successive washes each of 2 ml saline. This procedure removed about 80 per cent. of the total surfactant originally present and the surfactant content of the lung was restored to normal within 24 hr. The same procedure however removed at most only about 25 per cent. of the total number of macrophages in the lung and although a second lavage performed immediately after the first removed large numbers of macrophages, if a delay of several hours elapsed between the two lavages, the yield of macrophages was greatly reduced. The reasons for this behaviour are not understood, and it is likely to be one of the factors which limits the frequency with which pulmonary lavage can be repeated.