Assessing Apoptosis of Developing T Cells by Flow Cytometry

Apoptosis is a highly regulated process by which eukaryotic cells undergo cell death (1 –4 ). Often synonymous with “cell suicide” and “programmed cell death,” apoptosis is distinguishable from another major form of cell death, necrosis, by a number of key morphological and biochemical features (3 –6 ). First and arguably most importantly, plasma membrane integrity is maintained throughout apoptosis. On the other hand, membrane damage is a key characteristic of necrosis, which often occurs as a result of gross tissue and cellular injury. The containment of cytosolic material during apoptosis likely abrogates inflammatory reactions which could be detrimental to normal biological events. Second, apoptosis is an active process and requires cellular energy to systematically activate both signaling and catabolic enzymes. Necrosis, on the other hand, occurs as a result of a loss in a cell’s ability to maintain energy levels and does not involve the regulated activation of signaling or enzyme cascades.