A practical note on the use of cytotoxicity assays.

In this study, four cytotoxicity detection assays and four cytotoxic mechanisms were compared in one cellular system. Cellular responses and their effects were characterized. The assays used are based on different modes of detection like LDH release, MTT metabolism, neutral red uptake and the ATP content of treated cells. As cytotoxic mechanisms were used the model agents triton X-100, chloroquine and sodium azide (which are common in cell culture) as well as an ion channel (NMDA) mediated excitotoxicity cell death (which is specific for the cell line used). We found major differences in the calculated EC(50)-values for the cytotoxic effect of choroquine (0.1 up to 200 mM) and for sodium azide (4 up to 1300 mM) depending on the assay used. Therefore, it is important to choose a suitable cytotoxicity assay depending on the supposed cell death mechanism. As this study compares the strengths and weaknesses of the most common assays, it can help to find the appropriate one.