Cell kinetics of pulmonary alveolar macrophages in the mouse.

The study of pulmonary alveolar macrophages (PAMs) involves two techniques, one following the migration of a cohort of labelled PAMs from the lung and the other involves the use of a continuous labelling method with [3H]TdR. In both studies, strikingly similar, probably biphasic curves are obtained that can be interpreted as indicating the existence of two proliferating cell populations with turnover times of approximately 10 days and approximately 35 days. It is suggested that one of these compartments is an intra-alveolar PAM population whilst the other probably represents a precursor population. It is also possible to interpret the data as indicating a single, and probably solely intra-alveolar, PAM population with a very skewed distribution of cell cycle times.