Gr-1⁺CD11b⁺ cell-induced unresponsiveness of pro-inflammatory T cells to suppression is IL-6 dependent.

<p>(a), Gr-1⁺CD11b⁺ cells were isolated from the spleen of 20-week old Apo E^−/− and C57BL/6 mice and EL-4 tumor-bearing mice. The mRNA expression of Arg 1, iNOS 2, TGF-β1 and IL-6 was measured by qRT-PCR. (b), CD4⁺CD25⁻ T cells from C57BL/6 mice were cultured with or without Gr-1⁺CD11b⁺ cells and Treg cells as well as 20 µg/ml IL-6 antibody, T cell proliferation was determined by [3H] thymidine incorporation. Data are the mean ± SEM (n = 4) of one representative experiment. Atherosclerotic Apo E^−/− mice were pre-treated i.p. with 100 µg RB6-8C5 mAb or Jak inhibitor tofacitinib (CP-690,550) 30 mg/kg twice a week, (c), Phosphorylation of stat1 and stat3 as well as Erk was detected by immunoblot. Shown is one representative experiment out of three. the serum levels of IL-6 (d), INF-γ (e), IL-17A (f) and TGF-β1 (g) were measured by ELISA. Data are the mean ± SEM (n = 4) of one representative experiment. Similar results were obtained in at least three independent experiments. n.s = not significant; *p<0.05, **p<0.01.