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. 2018 Jan 15;8:1773. doi: 10.3389/fimmu.2017.01773

Figure 1.

Figure 1

CXC chemokine ligand 12 (CXCL12)–CXCR4 interaction induces phosphorylation of S727-STAT3 and IL-10 production by chronic lymphocytic leukemia (CLL) cells. (A) CXCL12 phosphorylates S727-STAT3 in CLL cells through interaction with the CXCR4 receptor. CLL cells were stimulated with 250 ng/ml CXCL12 for 20 min, fixed, permeabilized, and stained for p-S727-STAT3. Exposure to 0.05 µM/ml of the STAT3 inhibitor cucurbitacin for 2 h or CXCR4 blocking antibody, prevented the CXCL12-induced S727-STAT3 phosphorylation (n = 19). (B,C) Cytoplasmic IL-10 expression by CLL cells after CXCL12 stimulation. CLL cells were cultured for 8–10 h with either 250 ng/ml CXC12 or 4 µg/ml CpG (positive control), followed by addition of Phorbol myristate acetate (PMA), ionomycin, and BFA (PIB), and then incubated for another 6 h before performing intracellular staining. CXCL12 induced an increase in IL-10+ CLL cells, both in frequencies (B) and in absolute counts (C).