Combined action of phthalocyanine photosensitization and gamma-radiation on mammalian cells.

The response of Chinese hamster cells and human lymphocytes to the combined action of photosensitization by chloroaluminium phthalocyanine tetrasulfonate and gamma-radiation was studied using colony-forming ability and [3H]thymidine incorporation following mitogenic stimulation respectively, as endpoints. The action of both treatments was usually additive regardless of the sequence of application. However, in human lymphocytes irradiated at low temperature, the photosensitization interacted synergistically with the subsequent ionizing radiation; in this experiment the initial photosensitization reduced the yield of micronuclei produced by gamma-radiation.