Skip to main content
. 2021 May 12;11(14):7029–7044. doi: 10.7150/thno.60040

Figure 4.

Figure 4

Macrophage-derived IL-6 promotes PD-1 expression in T cells via the IL-6/STAT3 transcription axes. (A) PD-1 expression on CD8+ T cells derived from Rab37 WT and KO in the presence of α-IL-6 treatment. (B, C) Depletion of macrophages by clodronate-liposomes in mice reduced IL-6 level in LLC allografts (B) and decreased the PD-1 expression on the tumor-infiltrating CD8+ T cells (C). Scale bars: 100 µm. (D-F) Levels of IL-6 in the CM (D, E) and PD-1 mRNA of Jurkat T cells (D, F) derived from of mono-culture of THP-1 macrophages, A549 cancer cells or Jurkat T cells or in those of co-cultured conditions as indicated. Levels of IL-6 (D, E) and PD-1 mRNA (D, F) of Jurkat T cells co-cultured with THP-1 cells with Rab37 (siRab) knocked down or treated with α-IL-6 are shown. (G) ChIP-qPCR primers designed in P1, P2 and P3 regions of PD-1 promoter are indicated below the map. Sequences of the STAT3 binding motif are shown (left) and STAT3 binding sites are specified as boxes in the map (top). (H) p-STAT3 bound to PD-1 promoter. ChIP-qPCR assay was performed using anti-p-STAT3 antibody in Jurkat T cells treated with mixed CM with or without α-IL-6 treatment. IgG was used as negative control. Data represent mean ± SD. * p < 0.05; ** p < 0.01; *** p < 0.001; ns non-significant, Student's t-test.