A dye (Neutral Red) uptake method by using cultured human cancer cells and an application of this method to a sensitivity test for anti-cancer drug are described. The amount of Neutral Red (NR) taken by the cells was proportional to the concentration of NR added. The little additional dye was taken up by the cells after incubation for more than 60 min. In addition, the uptake of dye was linear to the number of viable cells by Trypan Blue exclusion. However, in vitro monolayer aging had an effect on the correlation between the uptake of dye and the number of viable cells. EC50s of mitomycin C, bleomycin, adriamycin, neocarzinostatin by this assay method were 0.11 μg/ml, 6.0 μg/ml, 0.054 μg/ml and 1.9 units/ml, respectively. This assay method is suited for a sensitivity test for anti-cancer drug because of its technical simplicity, convenience, allowing efficient handling of large number of specimens, precision and reproducibility.
