Non-myeloablative transplantation of bone marrow expressing self-antigen establishes peripheral tolerance and completely prevents autoimmunity in mice.

Myeloablative transplantation of bone marrow (BM) engineered to express myelin oligodendrocyte glycoprotein (MOG) establishes central intrathymic tolerance and completely prevents MOG-induced experimental autoimmune encephalomyelitis (EAE) in mice. Here we asked whether non-myeloablative transplantation of MOG expressing BM (pMOG-bone marrow transplantation (BMT)) can also provide the same protection. Using stepwise reduction of irradiation doses, 275 cGy irradiation with pMOG-BMT protected 100% of mice from EAE development even with two subsequent re-challenge with MOG. Irradiation doses <275 cGy produced dose-dependent partial protection with significant disease protection still evident at 50 cGy. Splenocytes from 275 cGy recipients proliferated to MOG stimulation in vitro, indicating that MOG-reactive cells are present in the periphery but failed to induce disease. MOG-stimulated splenocytes produced little or no interleukin-17, interferon-γ, granulocyte-monocyte colony stimulating factor and tumor necrosis factor-α compared with EAE control. Adoptive transfer of CD4 T cells from EAE-resistant mice into Rag2(-/-) mice devoid of MOG expression resulted in MOG-induced EAE in ~74% of mice. Treatment of EAE-resistant mice with anti-programmed death 1 (PD-1) monoclonal antibody-induced EAE in 67% of mice. We conclude that non-myeloablative transplantation of self-antigen expressing BM induces robust peripheral tolerance that completely prevented EAE development. Our findings implicate clonal anergy and the PD-1 pathway in the maintenance of peripheral tolerance.