**Stem Cell Transplantation for Primary Immunodeficiency**

Mary A. Slatter and Andrew R. Gennery

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/52796

### **1. Introduction**

In 1968, hematopoietic stem cell transplantation (HSCT) was first performed for patients with inherited cellular immunodeficiencies: a child with severe combined immune deficiency (SCID) and another with Wiskott–Aldrich syndrome (WAS) transplanted from matched siblings [1, 2]. Since then, HSCT techniques have advanced enormously due to refined HLA-tissue typing, the increased use of alternative donors, the availability of new stem cell sources including umbilical cord blood as well as less toxic chemotherapeutic conditioning [3], and graft-versus host disease (GVHD) prophylaxis. Supportive care has also improved, with molecular detection of viral infection enabling pre-emptive antiviral treatment before organ damage supervenes [4]. Greater awareness of primary immunodeficiency (PID) amongst general paediatricians, highlighted by campaigns promoting warning signs has lead to earlier diagnosis and referral to specialist centres[5]. Indications for HSCT increase as advances in molecular immunology better define PIDs while parallel studies of the natural history of PIDs reveal which will benefit most from early HSCT before organ damage is present[6]. There are now nearly 200 molecularly defined PIDs. HSCT aims to give stable donor stem cell engraftment after partial or full ablation of the recipient's marrow and immune system using a combination of chemotherapy, antibody therapy, and a graft-versus-marrow effect. [7] Nearly 1,500 children in Europe who have received allogeneic HSCT for PIDs[8] were reported recently, as well as over 1,000 children from Northern America in 2008.[9] Overall survival has increased to 90% for SCID babies with a genoidentical donor and nearly 70% for those given matched unrelated donor (URD) HSCT. For non-SCID PIDs, the survival for both genoidentical and URD HSCT is between 70% and 80%.[8] Together with improved survival advances have led, and continue to focus on, improved quality of life longterm.

© 2012 Slatter and Gennery, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
