Role of Regulatory T Cells in Tumor-Bearing Mice Treated with Allo-Hematopoietic Stem Cell Transplantation Plus Thymus Transplantation

Figure 2

Theory of allo-HSCT + TT for tumors. Untreated controls bearing tumor tissue showed increased numbers of T_reg cells, including iT_reg cells, with tumor progression (a). In the case of conventional allo-HSCT (b), the allo-T_eff and T_reg cells develop with tolerance and reactivity to the host in the thymus. A low GVT effect is then induced with no/minimal GVHD. Mild tumor regression is induced compared with untreated controls (a). The proportion of T_reg cells still increases slightly or is at the normal level. In the case of allo-HSCT + DLI (d), nontolerant and nonreactive allo-T_eff and T_reg cells are supplied externally, and a strong GVT effect occurs with strong GVHD. The proportion of T_reg cells decreases either slightly or markedly. In the case of allo-HSCT + TT (c), internally allo-partially tolerant T_eff and reactive T_reg are induced from the transplanted thymus. As a result, strong GVT occurs with mild GVHD. The proportion of T_reg cells decreases slightly or is at the normal level.

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