Treatment of the cells with a cytotoxic compound may result in necrosis, in which the cells lose their membrane integrity. Cell death or cytotoxicity is typically evaluated by quantifying plasma membrane lesions.

Adenylate kinase (AK) is a protein found in all eukaryotic and prokaryotic cells and is rapidly released into the culture medium after damage to the plasma membrane.

The bioluminescence cytotoxicity assay kits are based on the measurement of AK in a simple one-step procedure involving two chemical reactions. The first reaction converts ADP to ATP by the adenylate kinase released by the damaged cells. The second reaction uses luciferase to catalyze light formation from ATP and luciferin. This light is then measured using a luminometer or a beta counter. The test is very sensitive and can be fully automated for high throughput applications.