A novel cell permeant and far red-fluorescing DNA probe, DRAQ5, for blood cell discrimination by flow cytometry

The deep red fluorescing agent (DRAQ5) is a synthetic anthraquinone with a high affinity for DNA and a high capacity to rapidly enter living cells or stain fixed cells. DRAQ5 is optimally excited by red-light emitting sources and yields a deep red emission spectrum which extends into the low infra-r ed. DRAQ5 shows excitation at sub-optimal wavelengths including the 488 nm line and the multi-line UV wavelengths emitted by argon-ion lasers, Single beam (488 nm) flow cytometry has been used to demonstrate the utility of DR AQ5-nuclear DNA fluorescence as a discriminating parameter for human leucoc ytes and lymphoma cells, in combination with fluorochrome-labelled antibodi es for the detection of surface antigens omit subpopulation recognition. DR AQ5 fluorescence was found to reflect cellular DNA content as evidenced by cell cycle distribution profiles for asynchronous and cell cycle-perturbed populations. Importantly, DRAQ5 can be used in combination with FITC and RP E-labelled antibodies, without the need for fluorescence compensation. (C) 1999 Elsevier Science B.V. All rights reserved.