Comparison of MTT and ATP-based assays for the measurement of viable cell number.

Cell viability assays are widely used to assess the effect chemotherapeutic drugs and other agents on cell lines and have shown promise for the prediction of tumour chemosensitivity. In this study we have compared two viability assays using Daudi and CCRF-CEM cell lines over a range of 1500-100,000 cells/well of a microplate. The ATP assay was able to detect the lower limit of 1563 cells/well with luminescence values at least 100 x background readings, while the MTT assay could not detect less than 25,000 cells/well above background readings. The ATP assay also showed better reproducibility and sensitivity when cells were grown in microtitre plates over several days, and is particularly useful for the measurement of viability with low cell numbers.