Detection by the comet assay of apoptosis induced in lymphoid cell lines after growth factor deprivation

Dysregulation of apoptosis contributes to various diseases such as neurodegenerative or aging disorders, autoimmune syndromes or cancers. Numerous experimental paradigms have been explored to characterize molecular and cellular modulators of apoptosis. Similarly, numerous techniques have been described for detecting and/or quantifying accurately cells committed to apoptosis. Besides the conventional techniques, we describe in this report that the comet assay, which detects DNA single- and double-strand breaks in situ, at the cellular level, is relevant for the characterization of apoptotic cells. The comet assay is very sensitive and detects DNA fragmentation occurring in the apoptotic process as early as exposure of phosphatidylserine residues on the outer leaflet. Thus the comet assay can be used for the recognition of apoptosis that follows the death signal caused, for example, by genotoxic stress as well as lack of survival signal as in growth factor deprivation.