title: Persistence of host-type hematopoiesis after allogeneic bone marrow transplantation for leukemia is significantly related to the recipient's age and/or the conditioning regimen, but it is not associated with an increased risk of relapse.
abstract: We investigated the chimerism pattern within flow-sorted peripheral blood- or bone marrow-derived cell populations after allogeneic bone marrow transplantation (BMT) for the treatment of leukemia in children. This study was performed to define the identity of persistent host-type cells, to identify prognostic variables for the persistence of host-type hematopoiesis, and to determine the prognostic significance of the chimerism pattern on the duration of the leukemia-free interval, the overall survival, and the leukemia-free survival. The patients received either HLA-identical non-T-cell-depleted (n = 46) or HLA nonidentical T-cell-depleted (n = 7) BMT. In the peripheral blood, the children showed either stable mixed chimerism (SMC; ie, persistent host-type hematopoiesis; n = 14), (transient) mixed T-lymphoid chimerism (MTLC; n = 9), or complete chimerism (CC; n = 30). In the bone marrow, only donor-type cells were found in children with either CC (n = 8) or MTLC (n = 2), and a mixture of donor- and recipient-type cells was found in children with SMC (n = 7). The persistence of host-type hematopoiesis (SMC) was significantly related to a lower age of the recipient, the type of conditioning regimen, a lower total body irradiation dose, T-cell depletion of the bone marrow graft, and the use of cyclosporine A for acute graft-versus-host disease prophylaxis. No significant differences were found between patients with (SMC) or without (CC/MTLC) persistent host-type hematopoiesis with respect to the duration of the leukemia-free interval, the overall survival, or the leukemia-free survival. We conclude that ablation of host-type hematopoiesis is not compulsory for long-term leukemia-free survival after allogeneic BMT for various hematologic malignancies.
authors.affiliation: Department of Pediatrics, Leiden University Hospital, The Netherlands.
authors.forename: J E
authors.initials: JE
authors.lastname: van Leeuwen
authors.forename: M J
authors.initials: MJ
authors.lastname: van Tol
authors.forename: A M
authors.initials: AM
authors.lastname: Joosten
authors.forename: J T
authors.initials: JT
authors.lastname: Wijnen
authors.forename: P J
authors.initials: PJ
authors.lastname: Verweij
authors.forename: P M
authors.initials: PM
authors.lastname: Khan
authors.forename: J M
authors.initials: JM
authors.lastname: Vossen
mesh_terms: D000293:Adolescent; D000367:Age Factors; D016026:Bone Marrow Transplantation; D002648:Child; D002675:Child, Preschool; D005260:Female; D005434:Flow Cytometry; D006410:Hematopoiesis; D006801:Humans; D007223:Infant; D007938:Leukemia / Q000401:mortality / Q000628:therapy*; D008297:Male; D011379:Prognosis; D012008:Recurrence; D012306:Risk; D014184:Transplantation, Homologous