Isoenzyme analysis as a rapid method for the examination of the species identity of cell cultures

Summary One of the major problems in cell culturing is the misidentification or cross-contamination of authentic continuous cell lines. We applied a rapid and efficient isoelectric focusing (IEF) technique for the routine analysis to detect interspecies contamination of cell cultures and for the identification of unknown animal cell lines. The method is based on the isoelectric separation of a specific set of intracellular enzymes which can be used to distinguish between cell lines of human, murine, or other mammalian origin. By means of preformed agarose gels, standardized conditions and equipment, this technique is especially applicable for routine work and allows the analysis of a large number of unknown samples with reproducible results. One hundred seventy-seven cell lines which have been sent to the Department of Human and Animal Cell Cultures at the DSM (Deutsche Sammlung von Mikroorganismen and Zellkulturen) were analyzed for species authentication; only three cell lines were found not to be of the presumed species. Our study strongly emphasizes standardized IEF as an efficient and rapid method for routinely monitoring the authenticity of cell lines.