Allograft dendritic cell p40 homodimers activate donor-reactive memory CD8+ T cells
Hidetoshi Tsuda, Charles A. Su, Toshiaki Tanaka, Katayoun Ayasoufi, Booki Min, Anna Valujskikh, Robert L. Fairchild
Hidetoshi Tsuda, Charles A. Su, Toshiaki Tanaka, Katayoun Ayasoufi, Booki Min, Anna Valujskikh, Robert L. Fairchild
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Research Article Immunology Transplantation

Allograft dendritic cell p40 homodimers activate donor-reactive memory CD8+ T cells

Abstract

Recipient endogenous memory T cells with donor reactivity pose an important barrier to successful transplantation and costimulatory blockade–induced graft tolerance. Longer ischemic storage times prior to organ transplantation increase early posttransplant inflammation and negatively impact early graft function and long-term graft outcome. Little is known about the mechanisms enhancing endogenous memory T cell activation to mediate tissue injury within the increased inflammatory environment of allografts subjected to prolonged cold ischemic storage (CIS). Endogenous memory CD4+ and CD8+ T cell activation is markedly increased within complete MHC-mismatched cardiac allografts subjected to prolonged versus minimal CIS, and the memory CD8+ T cells directly mediate CTLA-4Ig–resistant allograft rejection. Memory CD8+ T cell activation within allografts subjected to prolonged CIS requires memory CD4+ T cell stimulation of graft DCs to produce p40 homodimers, but not IL-12 p40/p35 heterodimers. Targeting p40 abrogates memory CD8+ T cell proliferation within the allografts and their ability to mediate CTLA-4Ig–resistant allograft rejection. These findings indicate a critical role for memory CD4+ T cell–graft DC interactions to increase the intensity of endogenous memory CD8+ T cell activation needed to mediate rejection of higher-risk allografts subjected to increased CIS.

Authors

Hidetoshi Tsuda, Charles A. Su, Toshiaki Tanaka, Katayoun Ayasoufi, Booki Min, Anna Valujskikh, Robert L. Fairchild

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Figure 4

Endogenous memory CD8+ T cell proliferation in allografts subjected to prolonged CIS requires recipient graft class II MHC expression.

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Endogenous memory CD8+ T cell proliferation in allografts subjected to p...
(A) Cardiac allografts from WT C57BL/6 or B6.class II–/– mice or from A/J hearts were subjected to 0.5 or 8 hours of CIS and transplanted to groups of A/J mice (n = 5–10). On days 0 and 1 after transplant, all graft recipients were injected with 100 μg BrdU i.p. The next day, allografts were harvested and digested, and aliquots of single cell suspensions were stained with antibody and analyzed by flow cytometry, with examples of gating as shown for each allograft sample to assess and quantitate the BrdU incorporation of infiltrating memory CD4+ and CD8+ T cells. *P < 0.05, **P < 0.01, as determined by the Mann-Whitney nonparametric test. (B) The survival of MHC class II–deficient allografts or WT C57BL/6 allografts subjected to 8 hours of CIS in A/J recipients treated with 250 μg control rat IgG or CTLA-4Ig i.p. on days 0 and 1. Allograft survival was monitored by daily abdominal palpation, and rejection was confirmed by laparotomy. **P < 0.01 versus survival of WT C57BL/6 and MHC class II–/– allografts in IgG-treated A/J recipients; *P < 0.05 vs. survival of WT C57BL/6 allografts in CTLA-4Ig–treated recipients.