Isolation and identification of Clara cells from rabbit lung

A procedure has been developed for the isolation of nonciliated bronchiolar epithelial cells (Clara cells) from rabbit lung. Following pulmonary lavage to eliminate macrophages, cells (5% Clara cells) were released by digestion with 0.1% Protease I in HEPES-buffered balanced salt solution containing 0.5 mM ethylene glycol-bis-(beta-aminoethyl ether)-N,N'-tetraacetic acid instilled through the trachea. These cells were then separated on the basis of size using the Beckman JE-6 elutriator rotor. The fourth fraction collected from the elutriator contained about 30% Clara cells. This fraction was then layered on a two-polymer aqueous phase system consisting of 5% dextran T500 (DT) and 3.8% polyethylene glycol 6000 (PEG) in sodium phosphate buffer. A cell fraction was obtained from the PEG phase, which included approximately 70% Clara cells. These cells were found to be greater than 90% viable by trypan blue dye exclusion. Identification of isolated Clara cells was confirmed by light microscopic observation of nitro blue tetrazolium staining and by ultrastructural characteristics as observed by electron microscopy.