Ethylene Carbodiimide Fixed Donor Splenocytes Combined with alpha-1 Antitrypsin Induce Indefinite Donor Specific Protection to Mice Cardiac Allografts.

Peritransplant infusion of ethylene carbodiimide-fixed donor splenocytes (ECDI-SPs) induces protection of islet and cardiac allografts. However, pro-inflammatory cytokine production during the peritransplantation period may negate the effect of ECDI-SPs. Therefore, we hypothesized that blocking pro-inflammatory cytokine secretion while increasing levels of anti-inflammatory cytokines would enhance the tolerance-induced efficacy of ECDI-SPs. The objective of this study was to determine the effectiveness of using ECDI-SPs combined with a short course of alpha 1-antitrypsin (AAT) for induction of tolerance. Using a mice cardiac transplant model, we demonstrated that ECDI-SPs + AAT effectively induced indefinite mice cardiac allograft protection in a donor-specific fashion. This effect was accompanied by modulation of cytokines through decreasing levels of proinflammatory cytokines (including IFN-gamma, TNF-alpha, IL-1 beta, IL-6, IL-17, and IL-23) and increasing levels of anti-inflammatory cytokines (including IL10, IL-13, and TGF-beta), and by inhibition of effector T cells (Teff) and expansion of regulatory T cells (Tregs). Therefore, we concluded that combined ECDI-SPs and AAT appeared to modulate the expression of cytokines and regulate the Teff: Treg balance to create a support milieu for graft protection. Our strategy of combining ECDI-SPs and AAT provides a promising approach for inducing donor-specific transplant tolerance.