Modified neutral comet assay for human lymphocytes

Abstract

Comet assay under neutral conditions allows the detection of DNA double-strand breaks, considered to be the bio- logically relevant radiation-induced lesion. In this report we describe modifications of the neutral comet method, which sim- plify and facilitate its use for estimation of DNA double strand breaks in human lymphocytes irradiated with doses of 60 Co gamma-rays (from 10 to 100 Gy). The analysis carried out according to this protocol takes less time than those published so far. Also, the use of lysis at 50°C is avoided; this is important in view of the presence of heat-labile sites in the DNA of irra- diated cells, recently reported by Rydberg (12). The comets have well defined, sharp limits, are suitable for computer image analysis and chromatin of the control cells remains condensed.