FLUORESCENT ERYTHROCYTE-GHOSTS AS STANDARDS FOR QUANTITATIVE FLOW-CYTOMETRY

We report here a quick and inexpensive method for preparing standards of known fluorochrome content for calibration and quantitation of flow cytometry fluorescence signals. Erythrocyte ghosts prepared by hypnot ic lysis are filled with solutions containing fluorescently labeled de xtran. Standards prepared by this technique have a narrow range of flu orescence and a linear response of fluorescence to fluorochrome conten t up to 2 x 10(6) fluorochrome molecules/cell. The volume of ghost sta ndard particles is roughly 70 femtoliters (fl)/cell. The fluorescence of ghost standards is nearly identical to that of commercially availab le microbead standards of similar fluorochrome content. Ghost standard s have stable fluorescence for at least 3 weeks at 4 degrees C. These standards can be made with any fluorochrome or combination of fluoroch romes over a wide concentration range.