Cellular interactions in pulmonary oxygen toxicity in vitro: I. Hyperoxic induction of fibroblast factors which alter growth and lipid metabolism of pulmonary epithelial cells.

Pulmonary fibroblasts exposed to hyperoxic conditions in vitro release factors into their culture medium which influence the growth and lipid synthesis of tumor and nontumor pulmonary epithelial cells, but not pulmonary fibroblasts. These factors may be either inhibitory or stimulatory, depending on the degree and duration of hyperoxic exposure. Two stimulatory heat-labile factors have been tentatively identified by gel filtration. A growth-stimulating factor induced by hyperoxia has an apparent molecular weight approximately 20,000-26,000 daltons; a factor tht stimulates lipid synthesis has an apparent molecular weight approximately 8000 daltons. These factors appear distinct from other pneumocyte-specific peptides which occur in response to steroid therapy or pneumonectomy.