Identification of T cells, B cells, and Natural Killer (NK) cells is a common immunophenotyping method in flow cytometry analysis. Necrotic, apoptotic, and/or damaged cells can often interfere with data interpretation. These cells can be identified and excluded from viable cells through the use of viability dyes. Damaged and permeable cellular membranes permit the intercalation of impermeant viability dyes into nuclear DNA. Beckman Coulter currently offers three impermeant viability dyes which are excited by three different lasers: 7-AAD (excited by the blue laser), DRAQ7 (excited by the red laser), and DAPI (excited by the violet laser). To demonstrate the utility of these viability dyes for flow analysis, we designed an 8-marker 7-color panel leaving channels available for the drop-in of each viability dye. The panel contained the following antibodies: HLA-DR FITC, CD16 PE, CD56 PE, CD19 ECD, CD4 PC7, CD8 APC, CD3 APC-Alexa Fluor 750, and CD45 Krome Orange.
DRAQ7 is a far-red fluorescent DNA dye that only stains the nuclei in dead and permeabilized cells. It can be combined with other common fluors, especially GFP fusions & FITC and PE labeled antibodies as it has no UV excitation and emission overlap with these fluorochromes/dyes. Additionally, DRAQ7 is non-toxic in long term cultures; thus can be used for routine monitoring of cell health and status. As DRAQ7 only intercalates into DNA, no RNAse treatment is required for analysis. Lastly, as DRAQ7 is stable at room temperature and does not photobleach, solutions may be kept by cell culture/cell preparation areas for easy, quick usage.