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. 2020 Nov 18;15(11):e0242092. doi: 10.1371/journal.pone.0242092

Fig 4. M-MDSC suppression of T cell response requires cell-contact and is dependent on TGF-β.

Fig 4

(A) The autologous culture of CD4+ T cells and sorted M-MDSC in an indicated ratios (T cell: M-MDSC 1:1, 1:2 and 1:4) from PBMC of T1D subjects (n = 4) were performed with the two-chamber transwell system (gray bars) and without the transwell system (white bars). The suppression of CD4+ T cell proliferation was significant only in the culture without the transwell system and in the ratio 1:1. The black bars indicate the control proliferation of T effectors (eff) activated by anti-CD3/CD28 beads and without the activation. *p≤0.05, **p≤0.01, ***p≤0.001 (paired t-test). (B) CD4+ T cells were co-cultured with autologous sorted M-MDSC from T1D patients (n = 4). The particular inhibitors, Nor-NOHA–arginase-1 inhibitor, L-NMMA–iNOS inhibitor and anti-TGF-β mAb were added. The suppression of T cell proliferation by M-MDSC was significantly dependent on TGF-β and appeared to be independent of iNOS and arginase—1. The black bars indicate the control proliferation of T effectors (eff) activated by anti-CD3/CD28 beads and without the activation. *p≤0.05, **p≤0.01, ***p≤0.001 (paired t-test).