Bone marrow or peripheral blood as a source of stem cells for allogeneic transplants.

Peripheral blood stem cell transplants are being increasingly used in the allogeneic setting and are often preferred to the conventional bone marrow source. The aim of this report is to review available data on peripheral blood versus bone marrow hematopoietic stem cell transplantation. The discussion is restricted to HLA-identical sibling transplants receiving unmanipulated grafts. This is because data with appropriate follow-up are available only for this type of comparison: we have preliminary data on the use of peripheral blood from unrelated donors, and on the use of T-cell depletion/CD34+ selection methods. The latter are evolving rapidly and it may be difficult to find a concurrent group of patients receiving T-cell-depleted or CD34-selected marrow. The results of retrospective and prospective studies are similar: hematologic and immune recovery are faster after peripheral blood grafts, acute graft-versus-host disease is comparable, whereas chronic graft-versus-host disease is increased in recipients of peripheral blood transplants. Transplant-related mortality is similar in the two groups, whereas disease recurrence is lower after peripheral blood grafts. The general opinion is that peripheral blood grafts are indicated for patients with advanced disease, whereas for patients with early-phase disease the two sources may give comparable results.