New possibilities of cytostatic drug testing on patient tumor cells by flow cytometry

A new assay for cytostatic drug testing is described which can be automated. Pleural effusions and ascites are cultured as such for one week. Cells of solid tumors are cultured in the patients own serum for the same time. The cells are then stained with the esterase and intracellular pH-indicator dye 1,4-diacetoxy-2,3-dicyano-benzene (ADB) to label vital cells. They are simultaneously stained with propidium iodide (PI) as an indicator for dead cells. Monosized fluorescent latex particles are added as concentration, volume and fluorescence standard. Inflammatory cells can be distinguished in the assay from tumor cells because of their small cell volume. The number of dead and surviving cells is counted by the flow cytometer and a therapeutic index is calculated as ratio between the surviving inflammatory to surviving tumor cells. An important feature of the assay is that the DNA-distribution of the dead cells (e.g. aneuploidy) as well as the functional state of the surviving tumor cells and inflammatory cells can be judged from intracellular esterase activity and intracellular pH.