Cloning of human lung cancer cells.

We have carried out a comparison of two different methods for cloning human lung cancer cells. The method of Courtenay & Mills (1978) generally gave higher plating efficiencies (PE) than the method of Carney et al. (1980). The number of colonies increased with incubation time in both methods and the weekly medium replenishment in the Courtenay method was advantageous for longer incubation times of several weeks. In the Courtenay method, the use of August rat red blood cells (RBC) and low oxygen tension were both found to be necessary factors for maximum plating efficiency. The usefulness of heavily irradiated feeder cells in improving PE is less certain; each cell type may have its own requirement.