ECDI-fixed allogeneic splenocytes combined with α1-antitrypsin prolong survival of rat renal allografts

•Donor ECDI-SPs + AAT significantly decrease pro-inflammatory cytokines production and enhance anti-inflammatory cytokines production.•Donor ECDI-SPs + AAT significantly expand CD4+Foxp3 + Tregs in tolerant recipients and express a potent ability to suppress Teff responses.•Donor ECDI-SPs + AAT significantly enhance anti-donor cellular responses in tolerant recipients.•Donor ECDI-SPs significantly prolong renal allograft survival, and in combination with AAT promote permanent renal allograft function.

Pre- and post-transplant infusions of donor splenocytes treated with 1-ethyl-3-(3′-dimethylaminopropyl)-carbodiimide (ECDI-SPs) induce donor-specific tolerance and prolong rat renal allograft survival. However, proinflammatory cytokine production during peritransplantation negates the effects of ECDI-SPs. Therefore, we reasoned that blocking proinflammatory cytokines would promote long-term ECDI-SP-induced allograft survival. We therefore examined the effects of infusing ECDI-SPs alone or in combination with a short course of α1-Antitrypsin (AAT) on the long-term outcomes of a rat kidney allograft model. The data showed that ECDI-SPs + AAT promote renal allograft survival compared with ECDI-SPs alone. This effect was accompanied by expansion of Foxp3 + Tregs, enhanced alloantigen-specific Treg function, and modulation of expression levels of proinflammatory cytokines IL-1β, IL-6, TNF-α, and the anti-inflammatory cytokine IL-10. In conclusion, our strategy of combining ECDI-SPs and AAT provides a promising approach for inducing specific transplant tolerance.