Standard quantitative assays for apoptosis.

The term apoptosis refers to a peculiar morphology of cell death. It is of special interest because it can be triggered physiologically (and pathologically), and it is regulated by the actions of specific gene products. Therefore, it can in principle be activated and suppressed by medical intervention. It thus is often important to determine whether cells are dying by apoptosis (or its less regulated counterpart, necrosis) and also to quantity the effect in a population of cells. Here the classic methods of apoptosis quantitation are described; they will be of particular use to those whose laboratories are set up for standard microscopical and biochemical techniques, who do apoptosis assays infrequently but wish them to be widely accepted and reproducible. A simple microscopic observation, using blue light illumination and a pair of fluorescent dyes, is recommended for most applications.