A comparison of the in vitro susceptibility of HeLa and protozoan cells to antitumor antibiotics.

The relative in vitro susceptibility of HeLa cells and three protozoan species to a number of fermentation-derived materials was determined. Of the 61 purified agents tested in tube dilution and plate diffusion tests, 35 had displayed antitumor activity in rodents. The test system found to be most sensitive to the antitumor agents was that employing HeLa cells. Among the protozoan species, the descending order of sensitiv ity to tumor-active agents was as follows: Tetrahymena pyriformis, Ochromonas malhamensis, and Crithidia fasciculata. This order was not maintained in tests with the 26 tumor-inactive agents, since 0. malhamensis showed the greatest susceptibility and C. fasciculata the least, while HeLa cells and T. pyriformis were intermediate. In tests with tumor-active and tumor-inactive fermentation beers, the HeLa test system very effectively distinguished between them, whereas all the protozoan species proved to be relatively poor detectors of beer antitumor agents.