Stem Cell Transplantation for Primary Immunodeficiency

Primary immunodeficiencydiseases (PID) are a group of heterogeneous inherited disorders affecting the development and function of the innate and acquired immune system. The disorders are characterized by increased susceptibility to recurrent and severe infections, autoimmunity and in some cases malignancies. Allogeneic haematopoietic stem cell transplant (HSCT), and in some cases gene therapy, is the only curative approach for many of these disorders. With the expanding field of molecular genetics, new immune disordersare being identified, but the role of HSCT or other therapy in these disorders remains to be determined. This chapter will review the current indications for HSCT in PID and will examine the specific challenges associated with HSCT in (1) severe combined immunodeficiency(SCID) where the landscape is changing due the introduction of newborn screening; (2) other combined immune deficiencies, some of which have only very recently been described; and (3) phagocytic and haemophagocytic cell disorders. The role of alternative therapies including gene therapy and thymic transplantation will also be discussed.