Validation Study on Five Cytotoxicity Assays by JSAAE-VII. Details of the MTT Assay

The inter-laboratory validation study on 5 cytotoxicity assays conducted by JSAAE has been described in the preceding articles (see Validation Articles I-VI in this issue). Presented here are precise data and the protocols on the MTT assay with two cell lines, HeLa S3 (SC) and SQ-5. Hand-plotted dose-response curves provided unexpected information otherwise difficult to assume from calculated ED50 values and accompanying outputs from the logistic analysis program, LAP-JSAAE. The characteristics of data files from 18 laboratories were visualized together with all the log(ED50) values. Variations on negative controls in the assay revealed technical competence characteristics of each laboratory. Generally low OD590 values have been obtained in the present MTT assay but high inter-laboratory reproducibility was observed with both cell lines. These results will supplement our understanding on the MTT assay carried out in the large-scale inter-laboratory validation.