[The cell populations of the lower lung and their response to stress. Interrelations between cells and secretions of inflammation mediators in the distal air spaces].

Broncho-alveolar cells (BAC) act as defence means in the lower respiratory tract and acinus; equally they determine the evolution of inflammatory phenomena, whatsoever its cause. Alveolar macrophages (AM) play an important role in the regulation of the immune response and presentation of antigen to lymphocytes. In the alveolar microclimate AM exert a suppressor effect. AM can be equally considered as true inflammatory cells, either through their own mediators or through the skewed pattern of cellular recruitment. Among these cells polymorphonuclear cells and eosinophils, present in small numbers in broncho-alveolar lavage (BAL) may be encountered in a number of pathological conditions. Finally, free mast cells probably play an important role in the induction of the inflammatory reaction in the distal air spaces.