Principle of assays:
Following the successful delivery of a lethal hit by cytotoxic lymphocytes, protease activities leading to cell death in individual target cells can be measured by flow cytometry or fluorescence microscopy. In each kit cleavage of a cell permeable fluorogenic substrate reports the following activities:

Measurements with GranToxiLux^® and PanToxiLux^TM are superior to bulk assays e.g., LDH and ⁵¹Cr release, in terms of both time (0.3-2.0 hr. vs. 4 hr.) and sensitivity (relatively weak CTL responses against subdominant epitopes are detectable).  In the figure below, CTL responses are detected with OncoImmunin's first generation cell- mediated cytotoxicity kit, CyToxiLux^®.  Earlier events, e.g., delivery of granzyme B and/or caspase-8 from CTLs into target cells, are now detectable by GranToxiLux^® or PanToxiLux^TM.