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 9

Endogenous memory CD8+ T cell proliferation within cardiac allografts subjected to prolonged CIS and CTLA-4Ig–resistant allograft rejection requires p40 homodimers.

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Endogenous memory CD8+ T cell proliferation within cardiac allografts su...
(A) Groups of C57BL/6 mice (n = 5/group) received A/J cardiac allografts or C57BL/6 isografts subjected to 0.5 or 8 hours of CIS. The indicated recipients of 8 hours of CIS allografts were treated with 200 μg control rat IgG or anti-CD4 mAb on days –3, –2, and –1 prior to transplant. On day 2 after transplant, serum and graft lysates were prepared and quantities of p40 homodimers and IL-12 p70 heterodimers were tested by ELISA. *P < 0.05, as determined by the Mann-Whitney nonparametric test. (B) Groups of C57BL/6 mice (n = 5/group) received A/J cardiac allografts subjected to 0.5 or 8 hours of CIS and the indicated recipients were injected with 200 μg recombinant p40 homodimers i.p. on days 0 and 1. All recipients were injected with 100 μg BrdU i.p. on days 0 and 1 after transplant; the next day, allografts were harvested and digested, and cell aliquots were stained with antibody and analyzed by flow cytometry to assess total numbers and numbers of proliferating memory CD8+ T cells infiltrating the grafts. *P < 0.05; **P < 0.01, as determined by the Mann-Whitney nonparametric test. (C) Groups of C57BL/6 mice (n = 4–7/group) received A/J cardiac allografts subjected to 0.5 or 8 hours of CIS, and on days 0 and 1, were treated with 200 μg control rat IgG or 250 μg CTLA-4Ig i.p. with or without 200 μg recombinant p40 homodimers i.p. Allograft survival was monitored by daily abdominal palpation and rejection confirmed by laparotomy. ***P < 0.001 vs. all other groups, as determined using the Log-rank/Mantel-Cox test.