CD40Ig treatment results in allograft acceptance mediated by CD8⁺CD45RC^low T cells, IFN-γ, and indoleamine 2,3-dioxygenase
J. Clin. Invest. Carole Guillonneau, et al. 117:1096 doi:10.1172/JCI28801 [Go to this article.]

Figure 6
IFN-γ and IDO mediate the effect of CD40Ig and of CD8⁺CD45RC^low T cells. (A) Graft survival after 1-MT or anti–IFN-γ mAb administration beginning the day of transplantation (d0) to CD40Ig-treated animals or to animals receiving adoptive transfers at 120 days after transplantation (d120). Heartbeat of nonrejected grafts after 1-MT or anti–IFN-γ administration was + compared with +++ in CD40Ig-treated or adoptively transferred recipients. Arrow indicates adoptive transfer and beginning of treatment with 1-MT. (B) Representative Western blot analysis of IDO expression in cardiac grafts from syngeneic, CD40Ig-treated, and adoptively transferred recipients at day 120. Histograms show quantification of IDO normalized to tubulin in 3–4 samples per group. **P < 0.01, syngeneic versus adoptively transferred grafts. (C) Confocal analysis of grafts from adoptively transferred or syngeneic recipients using anti-IDO (green) and anti-CD31 (red) antibodies. Merge analysis shows IDO expression almost exclusively restricted to ECs. The inserts represent staining using an irrelevant mAb (3G8) or rabbit serum. Identical results were obtained with 2 other grafts from adoptively transferred animals and 2 grafts from CD40Ig-treated animals. Original magnification, ×400. (D) Kynurenine in cultured supernatants. CD8⁺CD45RC^low or CD8⁺CD45RC^high T cells from CD40Ig-treated recipients (n = 2 in each group) were cultured for 2 days with ECs from LEW.1W animals in the presence of anti–IFN-γ or control mAb (3G8) at 20 μg/ml. Levels are expressed as μM ± SD. *P < 0.05. (E) Quantitative RT-PCR analysis of IDO mRNA in ECs cultured for 2 days with CD8⁺CD45RC^low or CD8⁺CD45RC^high T cells from CD40Ig-treated recipients (n = 3 in each group). **P < 0.01 for CD8⁺CD45RC^low versus CD8⁺CD45RC^high.