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 neurodeg enerative or aging disorders, autoimmune syndromes or cancers. Numerous exp erimental paradigms have been explored to characterize molecular and cellul ar modulators of apoptosis. Similarly, numerous techniques have been descri bed for detecting and/or quantifying accurately cells committed to apoptosi s. Besides the conventional techniques, we describe in this report that the comet assay, which detects DNA single- and double-strand breaks in situ, a t the cellular level, is relevant for the characterization of apoptotic cel ls. The comet assay is very sensitive and detects DNA fragmentation occurri ng in the apoptotic process as early as exposure of phosphatidylserine resi dues on the outer leaflet. Thus the comet assay can be used for the recogni tion of apoptosis that follows the death signal caused, for example, by gen otoxic stress as well as lack of survival signal as in growth factor depriv ation.