A NEW CYTOCOLORIMETRIC ASSAY USING PHOSPHATAS E ACTIVI T Y FOR MEASURING CELLULAR FUNCTIONS

In this study cellular phosphatase activity, referred to as enzyme developed color (EDC) assay, was used for an in vitro assessment of cell proliferation and cytotoxicity. Optimum conditions were established and found to be 10 x103 cells / well at 37°C and 60 min incubation (for developing color). Under the same conditions a direct correlation between optical density (00) and cell number was observed. Thus, the ODs for a cell line, Ish at 100, 50, 25 and 10 X 103 cells/well were 1.0S ±0.05, 0.59 ±0.02, 0.33 ±0.02, and 0.17 ±0.01 respectively (r=0.995,p<0.001). When EDC was compared with another colorimetric assay, i.e. MTT, the results showed a direct correlation with r=0.995, p0.05), 0.19±0.01 (p>0.05), respectively. The assay was also shown to be suitable for the measurement of cell cytotoxicity and compared well with the MTT assay. These findings indicated that a simple, rapid and economical EDC assay could be used to investigate various cellular functions. The main advantage of EDC is it's suitability to use stored cells. This provides flexibility for testing samples stored over a long period in order to limit inter-experimental variations