Various Costimulatory Pathways Are Essential for Induction of Regulatory Cells by Intratracheal Delivery of Alloantigen

Abstract

Background We previously reported that intratracheal delivery of alloantigen induced regulatory cells in a mouse heart transplantation model. We investigated the roles of costimulatory pathways in the induction of regulatory cells by intratracheal delivery of alloantigen. Methods CBA (H-2 k) mice were pretreated with intratracheal delivery of splenocytes (1 × 10 7) from C57BL/10 (H-2 b) mice and administration of monoclonal antibodies (mAb) specific for programmed death (PD)-1 and its ligands, programmed death-ligand (PD-L)1 and PD-L2, CD70, CD134 ligand (CD134L), CD153, CD137L, or receptor activator of nuclear factor-κB (NF-κB) (RANK). Seven days later, naive CBA mice underwent adoptive transfer of splenocytes (5 × 10 7) from the pretreated CBA mice and transplantation of C57BL/10 heart. Results Adoptive transfer of splenocytes from CBA mice that had been pretreated with intratracheal delivery of C57BL/10 splenocytes significantly prolonged the survival of C57BL/10 allograft (median survival time [MST], 68 days) as compared with adoptive transfer from untreated CBA mice (MST, 12 days). Concomitant administration of control immunoglobulin (Ig)G, anti-PD-L2 mAb, or anti-CD137L along with intratracheal delivery did not significantly affect the prolongation (MST, 72, 68, and 65 days, respectively). In contrast, anti-PD-1, anti-PD-L1, anti-CD70, anti-CD134L, anti-CD153, or anti-RANK mAb abrogated the prolongation induced by adoptive transfer from the pretreated mice with intratracheal delivery (MST, 18, 17, 16, 14, 10, and 18 days, respectively). Conclusion The PD-1/PD-L1, CD27/CD70, CD134/CD134L, CD30/CD153, and tumor necrosis factor (TNF)–related activation-induced cytokine (TRANCE)/RANK interactions are independently required for generation of regulatory cells by intratracheal delivery of alloantigen.