Figure 7. T cell-derived CD70 inhibits allogeneic CD4⁺ T cell response.

Lethally irradiated BALB/c or FVB hosts were transplanted with CD4⁺CD25⁻ T cells purified from naïve C57BL/6 WT or CD70^−/− mice. (A) Kaplan-Meier survival curves of BALB/c hosts injected with 2×10⁴ CD4⁺CD25⁻ T cells and 3×10⁶ TCD BM. Data were summarized by combining 2 independent experiments (n=16 per group). (B) Kaplan-Meier survival curves of FVB hosts injected with 1×10⁶ CD4⁺CD25⁻ T cells and 3.5×10⁶ TCD BM. Data were summarized by combining 2 independent experiments (n=8 per group). (A–B) Statistical significance was determined by Log-rank test. (C–F) Lethally irradiated BALB/c hosts were injected with 5×10⁵ CD4⁺CD25⁻ T cells and 3×10⁶ TCD BM and sacrificed on Day 5. (C) Absolute numbers of CD4⁺ T cells were calculated by multiplying the total numbers of spleen cells by the percentages of TCRβ⁺CD4⁺ T cells present in spleen samples determined by flow cytometry. Summary data of caspase-8 activation (D) and caspase-3 activation (E) were combined from 3 independent experiments. (F) Summary data of CTLA-4, PD-1, TIM-3, and LAG-3 expression on TCRβ⁺CD4⁺ T cells at Day 5 after allo-HCT. Statistical significance was determined by unpaired student t test.