The acridine orange and dye exclusion viability tests applied to irradiated Ehrlich tumour cells.

Abstract

SummaryMice bearing an Ehrlich ascites tumour were given whole-body x-irradiation and sacrificed at intervals of one hour to three days after treatment. Specimens of ascites were removed and stained supravitally with acridine orange, eosin yellow or nigrosin. The viability of the ascites cells was assayed by observing their ability to produce new growths. The percentage of cells which showed unaltered cytoplasmic fluorescence after staining with acridine orange, or which did not absorb eosin or nigrosin, was significantly different from the percentage of cells which produced tumours. On the other hand, there was a good correlation between the results obtained with the two methods of assay when the cells were killed by treatment with formalin, alcohol or centrifugation. Fixed irradiated Ehrlich tumour cells showed a change in the cytoplasmic acridine orange fluorescence from red to orange or green. The percentage of cells showing this change increased with increasing dose, but did not correlate with the percentage of tumours produced by the irradiated ascites after subcutaneous injection.