Characterization of six textile dyes as fluorescent stains for flow cytometry

Few fluorescent stains specific for cell constituents other than DNA are available. To assess their potential use as fluorescent stains for flow cytometry, the cell staining specificity of 55 compounds, originally synthesized for use as textile dyes and fluorescent brighteners, was explored and their excitation and emission wavebands determined. From these, six dyes were chosen for more detailed analysis. All six are vital stains, with excitation wavelengths allowing their use with an argon ion laser, and specific for a range of cell structures including mitochondria, Golgi bodies, lipid droplets, nuclear membrane, and endoplasmic reticulum. Concentrations as low as 0.01-0.25 microM were found to be adequate for most purposes, and high background fluorescence was not a problem. Their specificity allows differentiation between non-cycling and cycling cells. The properties of two of the stains allows their combination with propidium iodide or ethidium bromide for simultaneous determination of DNA content profiles. Being vital stains, usable at very low concentrations, and specific for a range of cell organelles, these six stains may be of considerable utility in flow cytofluorometry. We suggest that other textile dyes may be of use in flow cytofluorometry, or that their structures may form a starting point for the synthesis of further fluorescent stains of enhanced specificity.