CD40Ig treatment results in allograft acceptance mediated by CD8+CD45RClow T cells, IFN-γ, and indoleamine 2,3-dioxygenase
Carole Guillonneau, … , Maria Cristina Cuturi, Ignacio Anegon
Carole Guillonneau, … , Maria Cristina Cuturi, Ignacio Anegon
Published April 2, 2007
Citation Information: J Clin Invest. 2007;117(4):1096-1106. https://doi.org/10.1172/JCI28801.
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Research Article

CD40Ig treatment results in allograft acceptance mediated by CD8+CD45RClow T cells, IFN-γ, and indoleamine 2,3-dioxygenase

Abstract

Treatment with CD40Ig results in indefinite allograft survival in a complete MHC-mismatched heart allograft model in the rat. Here we show that serial second, third, and fourth adoptive transfers of total splenocytes from CD40Ig-treated recipients into secondary recipients led to indefinite donor-specific allograft acceptance. Purification of splenocyte subpopulations from CD40Ig-treated recipients demonstrated that only the adoptively transferred CD8+CD45RClow subset resulted in donor-specific long-term survival, whereas CD8+CD45RClow T cells from naive animals did not. Accepted grafts displayed increased indoleamine 2,3-dioxygenase (IDO) expression restricted in the graft to ECs. Coculture of donor ECs with CD8+CD45RClow T cells purified from CD40Ig-treated animals resulted in donor-specific IDO expression dependent on IFN-γ. Neutralization of IFN-γ or IDO triggered acute allograft rejection in both CD40Ig-treated and adoptively transferred recipients. This study demonstrates for what we believe to be the first time that interference in CD40–CD40 ligand (CD40-CD40L) interactions induces allospecific CD8+ Tregs that maintain allograft survival. CD8+CD45RClow T cells act through IFN-γ production, which in turn induces IDO expression by graft ECs. Thus, donor alloantigen-specific CD8+ Tregs may promote local graft immune privilege through IDO expression.

Authors

Carole Guillonneau, Marcelo Hill, François-Xavier Hubert, Elise Chiffoleau, Caroline Hervé, Xian-Liang Li, Michèle Heslan, Claire Usal, Laurent Tesson, Séverine Ménoret, Abdelhadi Saoudi, Brigitte Le Mauff, Régis Josien, Maria Cristina Cuturi, Ignacio Anegon

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Figure 6

IFN-γ and IDO mediate the effect of CD40Ig and of CD8+CD45RClow T cells.

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IFN-γ and IDO mediate the effect of CD40Ig and of CD8+CD45RClow 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+CD45RClow or CD8+CD45RChigh 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+CD45RClow or CD8+CD45RChigh T cells from CD40Ig-treated recipients (n = 3 in each group). **P < 0.01 for CD8+CD45RClow versus CD8+CD45RChigh.