Detection by Flow Cytometry of Anti-DNA Autoantibodies and Circulating DNA Immune Complexes in Lupus Erythematosus

Figure 1

DNAse I and detergent sensitivity of serum particles detected by flow cytometry. The ordinate of histograms is the side scatter (SS) and the abscissa; the fluorescence of DNA stained by ethidium bromide (EB), measured at 620 nm (FL3). The discriminator was EB fluorescence; only events tagged by EB are shown. Upper histograms. (a) Calf thymus DNA (ctDNA) at 10 μg/ml. (b) A SLE serum sample with anti-DNA antibodies containing endogenous DNA (eDNA) and microparticles (MPs). MPs may be stained with EB because they may contain DNA. (c, d) The same serum sample incubated with 20 and 40 μg/ml ctDNA. (e) The serum sample after incubation with 20 μg/ml ctDNA was treated with DNAse I or (f) treated with Tween 80 diluted 1/1000. The arrows indicate size-calibrated 0.5, 0.9, 3, and 10 μm fluorescent beads. A microparticle gate was established using size-calibrated beads as described [27, 28].

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