Fluorometric determination of the DNA content of cells cultured in tissue culture plates.

Determining the DNA content of cultured cells with the fluorochrome diaminobenzoic acid (DABA) has been shown to be a sensitive and selective method. A procedure is described which applies this method to cells cultured in 96-well and 24-well plates. After removal of the medium, the cells are disrupted by sonication, dried and reacted with DABA. For the final read-out the DABA-DNA solution is transferred to standard cuvettes and the fluorescence intensity determined with a conventional fluorometer. The method is highly reproducible and suitable for the cell concentrations usually employed in microculture systems. It is an easy non-radioactive method for determining the numbers of both adherent and non-adherent cells, especially when comparing different stages of activation or differentiation.