Fig. 4.

a Gating strategy used to quantify STAT3 phosphorylation in transduced cells. In brief, transduced cells were gated as green fluorescent protein (GFP) + and within this population CD4+ and CD8+ T cells were gated and mean fluorescence intensities (MFI) were measured for phosphorylated STAT3 (pSTAT3; Y705) at 0, 15, and 45 minutes after IL-21 stimulation. b IL-21 induced STAT3 phosphorylation after miR-155 transduction. MFI of pSTAT3 (Y705) upon IL-21 stimulation in transduced cells from systemic lupus erythematosus (SLE) patients (n = 10) and healthy controls (HC) (n = 10) gated on CD4+ and CD8+ T cells. Phosphorylation of STAT3 was significantly higher after 15 minutes of IL-21 stimulation in both CD4+ and CD8+ T cells from SLE patients and HCs, but not at baseline or after 45 minutes. In brief, PBMCs were transduced using lentiviral vectors carrying either the GFP gene alone or genes encoding GFP and miR-155. *p < 0.05, **p < 0.01 (Mann–Whitney U-test). SSC side-scatter