Alternative fluorochromes to ethidium bromide for automated read out of cytotoxicity tests.

Propidium iodide (PI) and diamidinophenylindol (DAPI) were compared with ethidium bromide (EB) in cytotoxicity tests. Double blind studies showed similar results with the 3 dyes in terms of percentages of dead (fluorescing) cells. The dyes were also investigated for their potential combination with the immunofluorescent membrane markers FITC and TRITC. Both EB-FITC and PI-FITC are suitable for conventional HLA-DR typing procedures. Because of its spectral properties, the DAPI-TRITC combination is promising for automated read out of DR-typing tests by image analysis systems.