Psoralen photosensitization of L 1210 leukaemia cells: an approach to a new combined therapy.

Psoralen photosensitization of L 1210 cells has a strong effect on DNA and RNA syntheses and this result appears connected with the psoralen photobinding to DNA. Protein synthesis is less sensitive and its inhibition seems due to a different photochemical interaction, very likely to the psoralen photobinding to RNA. A combined therapy using cyclophosphamide and L 1210 cells psoralen-photoinactivated was performed after the leukaemia transplant, showing a significant decrease in mortality, even in comparison with the simple treatment with the alkilating drug.