Alveolar macrophage: origin, kinetics and relationship with cells of the alveolo-interstitial region.

The alveolar macrophage (AM) is the most abundant immunocompetent cell in the alveolus. Studies of this cell type have usually focused on its morphological, enzymatic or functional aspects but little attention has been paid to its origin or kinetics or to the functional relationship it has with local structures. There were two aims in this present work: firstly, to review the current data relating to the origin of this cell type, emphasizing the following aspects: Immediate and remote precursors of the alveolar macrophage. The proliferative capacity of the alveolar macrophage. Its routes of elimination. Regulating factors. Secondly, the main relationships of the alveolar macrophage with other cells of the alveolus and pulmonary interstitium were considered. This was done from two different viewpoints: The action of the alveolar macrophage on adjacent cells. The actions of local cells of the alveolar macrophage itself.