Effects of Preexisting Autoimmunity on Heart Graft Prolongation After Donor-Specific Transfusion and Anti-CD154

Abstract

Background Alloreactive memory T cells prevent costimulatory blockade-induced heart graft survival in mice, but whether and how preexisting autoreactive T cells affect solid organ transplants under these conditions is unknown. Methods We tested the impact of preexisting cardiac myosin (CM)-specific immunity on murine heart transplant recipients treated with donor specific transfusion (DST) plus anti-CD154 mAb MR1. Results Pre-immunization with CM but not control ovalbumin abrogated the graft prolonging effects of DST/MR1, whether administered 2 weeks or >6 weeks prior to transplantation. Adoptive transfer of spleen cells from CM-immunized mice into naïve recipients had similar effects. CM-specific immunity did not cross-react with donor antigens and pre-immunization with CM had no impact on the survival or histology of DST/MR1 treated syngeneic heart grafts, the latter indicating that persistent autoimmunity is insufficient to cause rejection in the context of costimulatory blockade. We observed that the CM-pre-immunized mice produced higher frequencies of donor-reactive T cells with higher ratios of CD8+/CD4+Foxp3+ cells, suggesting that the autoreactive memory T cells provide help for activation of alloreactive T cells despite the costimulatory blockade. Conclusions These mechanistic insights linking auto- and alloimmunity in a model of murine heart transplantation have clinical relevance to the known association between autoimmunity and an elevated risk of acute and chronic heart transplant injury in humans.

TLR-Induced Murine Dendritic Cell (DC) Activation Requires DC-Intrinsic Complement

“…Heterotopic heart transplants were performed as previously described by our lab (32, 43–45). For graft survival experiments, recipients were treated with anti-CD40L (anti-CD154) mAb MR1 (1mg on day 0 and 500μg on day7&14 i.p.)…”

Effect of Absent Immune Cell Expression of Vitamin D Receptor on Cardiac Allograft Survival in Mice

“…Heterotopic heart transplantation was performed as described (19, 20) by the microsurgery core facility at the Icahn School of Medicine at Mount Sinai. In some experiments recipient mice received anti-CD40L mAb (200µg - 500µg as indicated, Bio X Cell, West Lebanon, NH) i.v.…”

“…IFNγ ELISPOT assays were performed as described (19, 20). Briefly, single cell suspensions of spleen cells were cultured for 24 hours in HL-1 media (1% Penstrep 1% L-Glutamine) alone, with one of three titrations of OVA protein (10, 3, and 1µg/mL), cardiac myosin protein (specificity control), or Concanavalin A (positive control) in MultiScreeen HTS -IP ELISPOT plates (Millipore, Billerica, MA) precoated with anti-IFNγ coating antibody (BD Pharmingen).…”

Role of Memory T Cells and Perspectives for Intervention in Organ Transplantation

“…Endogenous memory T cells are not previously primed to donor antigens; however, a proportion of the endogenous memory T-cell repertoire in naïve mice is reactive with donor class I MHC molecules, and these T cells are rapidly detected and infiltrate into cardiac allografts within hours of reperfusion ( 17 ). In other selected models, memory T cells have been shown to be pivotal mediators of chronic allograft rejection, implying that memory T cells and chronic rejection may also be tightly associated ( 18 , 19 ). Therefore, despite the different mechanisms by which they are generated, memory T cells are capable of mediating rejection.…”