Resetting the immune system with immunoablation and autologous haematopoietic stem cell transplantation in autoimmune diseases.

Over the past 20 years, immunoablation followed by transplantation of autologous haematopoietic stem cells (ASCT) has emerged as a promising treatment option for patients with severe forms of autoimmune diseases (ADs) that insufficiently respond to standard immunosuppressive or novel biologic treatment. Meanwhile, mechanistic studies have provided the proof-of-concept that the long-term, treatment-free remissions achieved by ASCT are associated with the eradication of the autoreactive immunologic memory and a fundamental reconfiguration of the immune system. The latter comprises regeneration of naive B cells and a stable thymic reactivation with re-emergence of thymic-derived naive T cells, including Foxp3+ regulatory T cells, with new antigen receptors, i.e. immune reset. In this article, we discuss mechanistic studies that investigated how such immune renewal after ASCT may rewire a faulty immune system in ADs into a self-tolerant state, to induce long-term remissions.