Photosensitization of leukemia L1210 cells with diaziquone

Exposure of leukemia L1210 cells in culture to the drug diaziquone resulted in inhibition of incorporation of labeled thymidine into nucleic acid and loss of cell viability. These effects were markedly potentiated by irradiation of cells previously exposed to diaziquone in culture. This result shows that diaziquone can catalyze phototoxicity; the action spectrum of the drug may limit clinical applications of this phenomenon.