Figure 4.

CD4⁺CD8⁺ (DP) T cells from N3-tg mice induce CD11b⁺Gr-1⁺ MDSCs in NSG hosts. NSG recipients were transplanted i.v. with CD4⁺CD8⁺ (DP) T cells sorted from BM of N3-tg mice (DPtg; n = 3 donors) or from thymus of wt mice (DPwt; n = 3 donors), as a control. Each of the donors has two recipients. NSG recipients were sacrificed at 3–5 weeks (n = 3 NSG recipients per group) and 9–11 weeks (n = 3 NSG recipients per group) posttransplantation and analyzed by FACS. (A) Absolute numbers of CD11b⁺Gr-1⁺ cells in BM of NSG mice, recipients of DPwt or DPtg cells, assessed by FACS analysis, at 3–5 and 9–11 weeks posttransplantation. (B) Representative FACS analysis of in vitro suppression assay of activated/CFSE-labeled wt T splenocytes (“responders”), cultured either alone (Ctr), as a control, or in combination with CD11b⁺Gr-1⁺ cells (as putative “suppressors”), at the indicated CD11b⁺Gr-1⁺/responders ratio. Numbers inside cytograms indicate the percentages of proliferating wt CD4⁻CD8⁺ T responder cells. CD11b⁺Gr-1⁺ cells were sorted from BM of NSG hosts, at 9–11 posttransplantation with DPwt (CD11b⁺Gr-1⁺/DPwt) or DPtg (CD11b⁺Gr-1⁺/DPtg) cells. In (C), the results of suppression test, as in (B), are calculated as ratio between percentages of proliferating wt CD4⁻CD8⁺ T cells in CD11b⁺Gr-1⁺-containing cultures (CD11b⁺Gr-1⁺/DPwt or CD11b⁺Gr-1⁺/DPtg) and in control cultures set up in the absence of CD11b⁺Gr-1⁺ (Ctr) and are expressed as % of control. Data represent the mean values ± SD from three independent experiments (n = 3 mice per group), with two technical replicates per experiment in (C). ns, not significant, p > 0.05; ^* p ≤ 0.05, ^** p ≤ 0.01, and ^*** p ≤ 0.001 represent significant differences between the indicated groups.