Anti-C4d chimeric antigen receptor regulatory T cells suppressed allograft rejection in ABO-incompatible heart transplantation

Abstract Antibody-mediated rejection (ABMR) is one of the main obstacles to successful transplantation, including ABO blood group-incompatible (ABOi) transplantation. Recently, chimeric antigen receptor regulatory T cells (CAR Tregs) were developed to improve the antigen specificity, viability, and suppressive activity of Tregs. C4d deposition is a marker of ABMR and is also found in most ABOi allograft tissues. Based on these findings, we developed anti-C4d CAR Tregs to suppress ABMR in ABOi allografts. Anti-C4d CAR Tregs prepared by retroviral transduction of CAR into CD62L + CD4 + CD25 + Tregs, expressed Foxp3, CD25, CTLA-4, LAP, and GITR to similar extents as non-transduced Tregs. Anti-C4d CAR Tregs were activated by specific binding to C4d and suppressed in vitro T cell proliferation as well as nontransduced Tregs. Furthermore, adoptive transfer of anti-C4d CAR Tregs significantly prolonged mouse ABOi heart allograft survival (P