Figure 2. STAT3 inhibition with S3I-201 polarized STAT5 phosphorylation in allostimulated CD4⁺ T cells.

(A, B) Representative contour plots show gating strategy and histograms demonstrate reduced STAT3 phosphorylation in CD4⁺ alloresponders, with preservation of STAT5 activity, in 5 day allogeneic cocultures (DC:T cell ratio 1:30) treated with S3I-201 vs. DMSO without the addition of any exogenous cytokine. (A, B) Gates define the CD4⁺, pSTAT3⁺ and CD4⁺, pSTAT5^Bright T cells, respectively. (C, D) The mean ± sd of results in 3 independent experiments of STAT3 and -5 phosphorylation by geometric MFI ratio. (E) the frequency of CD4⁺, pSTAT5^Bright T cells, and (F) the CD4⁺, pSTAT5^Bright:pSTAT3⁺ ratio by percentage of phosphorylation, in CD4⁺ T cells harvested from S3I-201- or DMSO-treated 5 day allogeneic cocultures. *P < 0.05, **P=0.001–0.01, ***P = 0.0001–0.001, NS, by paired t test.