Isotope-release Cytotoxicity Assay

**Semantic type:** Research Activity

**Definition:** An assay that is used to quantify cytotoxic effector cell activity (e.g., cytotoxic T cell (CTL) or natural killer (NK) cell) by measuring target cell lysis. The process involves bathing and labeling the target cells with a radioactive isotope (e.g. Chromium 51 or Indium-111) or fluorescent molecule. The target cells are then mixed with the effector cells (CTL or NK). The killing of the labeled target cells leads to the release of the radioactive isotope into the supernatant after cell lysis. Accumulation of the radioactive isotope is quantified and measured in the supernatant which indicates effector cell-mediated cytolysis.

**Synonyms:** - ISOTOPE-RELEASE CYTOTOXICITY ASSAY