The Evolution of T Cell Depleted Haploidentical Transplantation

Work on bone marrow transplantation from haploidentical donor has been proceeding for over 20 years all over the world and new transplant procedures have been developed. To control both graft rejection and graft vs. host disease, some centers have preferred to enhance the intensity of the conditioning regimens and the post-transplant immune suppression in the absence of graft manipulation; others have concentrated on manipulating the graft in the absence of any additional post-transplant immune suppressive agent. Due to the current high engraftment rates, the low incidence of graft-vs.-host disease and regimen related mortality, transplantation from haploidentical donors have been progressively offered even to elderly patients. Overall, survivals compare favorably with reports on transplants from unrelated donors. Further improvements will come with successful implementation of strategies to enhance post-transplant immune reconstitution and to prevent leukemia relapse.

Patients with adenosine deaminase deficiency surviving after hematopoietic stem cell transplantation are at high risk of CNS complications

Adenosine deaminase (ADA) deficiency is a systemic metabolic disease that causes an autosomal recessive variant of severe combined immunodeficiency (SCID) and less consistently other complications including neurologic abnormalities. Hematopoietic stem cell transplantation (HSCT) is able to correct the immunodeficiency, whereas control of nonimmunologic complications has not been extensively explored. We applied HSCT in 15 ADA-deficient patients consecutively treated at our institutions since 1982 and analyzed long-term outcome. Seven patients received transplants without conditioning from HLA-matched family donors (MFDs); the other 8 patients received conditioning and were given transplants either from HLA-mismatched family donors (MMFDs; n = 6) or from matched unrelated donors (MUDs; n = 2). At a mean follow-up period of 12 years (range, 4-22 years), 12 patients are alive with stable and complete immune reconstitution (7 of 7 after MFD, 4 of 6 after MMFD, and 1 of 2 after MUD transplantation). Six of 12 surviving patients show marked neurologic abnormalities, which include mental retardation, motor dysfunction, and sensorineural hearing deficit. We were unable to identify disease or transplantation-related factors correlating with this divergent neurologic outcome. The high rate of neurologic abnormalities observed in long-term surviving patients with ADA deficiency indicates that HSCT commonly fails to control CNS complications in this metabolic disease.