Comet assay and early apoptosis

The comet assay is a single cell gel electrophoresis test currently used as a qualitative and quantitative genotoxicity test. However, some of the res ults from this comet assay and current knowledge on apoptosis lead us to su spect the presence of some false positive results. The aim of this study wa s to ascertain if apoptotic cells can yield comet images that might distort the interpretation of the results. Using Jurkat cells, that hardly express Fas antigen, and apoptosis induction with anti-Fas antibody, it was possib le to show that apoptosis can generate typical comet pictures as soon as th e cells enter the apoptosis process. Therefore, comet images cannot be inte rpreted as a genotoxicity indicator when an apoptosis risk is present. Yopr o-1 staining, that is also nearly immediate after apoptosis induction, can be used to balance comet assay results. (C) 2001 Elsevier Science B.V. All rights reserved.