Distinguishing necroptosis from apoptosis

Apoptosis was the first programmed cell death to be defined—highly regulated and immunologically silent, as apoptotic bodies are being removed without triggering inflammation. Few decades later, necroptosis was discovered—uniquely regulated but inflammatory. As these two programmed cell death pathways may be initiated via similar pathways (death receptors and intracellular receptors) while being differently regulated and resulting in distinctive physiological consequences, the need for distinguishing apoptosis from necroptosis is required. Here we describe a series of distinguishing assays that use apoptotic- and necroptotic-distinct response to pharmacological interventions with specific death inhibitors, morphology and death-specific proteins involvement. The procedure includes cell death kinetics assessment and morphology monitoring of stimulated and pharmacologically treated-cells using flow cytometry and live imaging, with the detection of death-specific proteins using Immunoblot. The procedure described here is simple and thus can be adjusted to various experimental systems, enabling apoptosis to be distinguished from necroptosis in one’s system of interest, without the need for more complex reagents such as genetic knockout models.