THE PULMONARY LIPOFIBROBLAST (LIPID INTERSTITIAL CELL) AND ITS CONTRIBUTIONS TO ALVEOLAR DEVELOPMENT

The pulmonary lipofibroblast is located in the alveolar interstitium a nd is recognizable by its characteristic lipid droplets. During alveol ar development it participates in the synthesis of extracellular matri x structural proteins, such as collagen and elastin, and as an accesso ry cell to the type II pneumocyte, in the synthesis of surfactant. The lipofibroblast contains cortical contractile filaments and is thereby related to the contractile interstitial cells that are normally found at the alveolar septal tips and after lung injury. The morphologic, i mmunologic, and biochemical characteristics of the lipofibroblast and its probable physiologic functions are reviewed. The retinoid and lipi d metabolism of the lipofibroblast is compared with that of the hepati c lipocyte and the adipocyte. Although the functions of the lipofibrob last remain incompletely characterized, this cell type is emerging as an important contributor to pulmonary alveolar septal development.