Measuring DNA damage using capillary electrophoresis with laser-induced fluorescence detection

Damage to cellular DNA is implicated in the early stages of carcinogenesis and in the cytotoxicity of many anticancer agents, including ionizing radiation. Sensitive techniques are required for measuring cellular levels of DNA damage. We describe in detail a novel immunoassay that makes use of the resolving power of capillary electrophoresis and the sensitivity of laser-induced fluorescence detection. An example is given of the detection of thymine glycol in DNA produced by irradiation of human cells with a clinical dose of 2 Gy. A detection limit of approximately 10(-21) mol allowed us to monitor the repair of the lesion and to suggest that the cellular repair response may be inducible.