Cord blood stem cell transplantation in primary immune deficiencies.

PURPOSE OF REVIEW Umbilical cord haematopoietic stem cell transplantation for primary immunodeficiencies is examined with other developments in treatment. Cord blood biology is reviewed, and advantages and disadvantages of umbilical cord blood stem cell transplantation for primary immunodeficiencies discussed. Clinical outcome data and future developments are reviewed. RECENT FINDINGS Cord blood T lymphocytes become tolerant to host human leukocyte antigen antigens, but retain alloreactivity to other antigens, in part due to immaturity of cord blood T lymphocytes and dendritic cells. Although naïve T lymphocytes can generate herpes virus specificity after transplantation, the risk of viral death is increased within the first 100 days. The clinical success of umbilical cord blood stem cell transplantation for primary immunodeficiencies is reviewed and new methods for expanding the stem cell number or encouraging engraftment with the use of third-party haematopoietic or mesenchymal stem cells examined. SUMMARY Many advantages make umbilical cord blood an attractive source of stem cells; over 100 umbilical cord blood stem cell transplantations have been performed for primary immunodeficiencies, with low rates of significant graft vs. host disease, despite significant human leukocyte antigen mismatch. Immune reconstitution is as good as for other stem cell sources: use of nascent stem cells in young recipients may have long-term advantages. Stem cell engineering to improve engraftment will expand potential beneficiaries of umbilical cord blood stem cell transplantation to older patients.