Complications of autologous hematopoietic stem cell transplantation for patients with autoimmune diseases.

Autologous hematopoietic stem cell transplantation (HSCT) has been used to treat severe and refractory autoimmune diseases (ADs) in children and adults for more than 15 years. The aim of this treatment is to restore tolerance through an intense lymphodepleting conditioning, and many patients have achieved lasting remissions. However, HSCT is associated with significant morbidity and mortality and is therefore not yet standard of care. Pre-existing reduced organ function of patients with ADs may increase the organ toxicity of conditioning. In the early post-HSCT phase, bacterial or fungal infections occur and therapy-associated lymphopenia sets patients at risk for reactivation of endogenous viruses and other opportunistic infections. During re-emerging of lymphopoiesis after HSCT, de novo autoimmunity may develop through loss of central or peripheral control mechanisms. Late effects of autologous HSCT (e.g., on the endocrine system) and a potentially increased frequency of secondary malignancies are of concern. The steadily increasing knowledge about specific complications occurring in patients with ADs after HSCT has led to the adaption of treatment protocols and has already reduced toxicity. Further prospective long-term follow-up studies are needed to identify patients at risk for developing serious complications after HSCT.