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Bone Marrow Research
Volume 2015 (2015), Article ID 176526, 6 pages
http://dx.doi.org/10.1155/2015/176526
Research Article

Very Long Term Stability of Mixed Chimerism after Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Hematologic Malignancies

1Department of Hemato-Oncology, Hôpital Fribourgeois, 1708 Fribourg, Switzerland
2Division of Hematology, Geneva University Hospital, 1205 Geneva, Switzerland
3Transplantation and Cellular Therapy Unit, Paoli-Calmettes Institute, 13009 Marseille, France
4Division of Hematology, Basel University Hospital, 4056 Basel, Switzerland

Received 2 September 2015; Accepted 22 October 2015

Academic Editor: César O. Freytes

Copyright © 2015 Emmanuel Levrat et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The objective of this study is to analyze the evolution of chimerism of all patients transplanted for hematologic malignancies in our unit during a 20-year period, alive without relapse at 1 year after allogeneic hematopoietic stem cell transplantation (HSCT). Chimerism was tested using short tandem repeat polymorphisms after separation into mononuclear cells and granulocytes by Ficoll density gradient centrifugation. Of 155 patients studied, 89 had full chimerism (FC), 36 mononuclear cells mixed chimerism (MNC-MC), and 30 granulocytic MC with or without mononuclear cells MC (Gran-MC). Survival was significantly better in MNC-MC than in Gran-MC patients, with FC patients being intermediate. There was more disease relapse in the Gran-MC group but not in the MNC-MC group as compared to FC. MC was stable up to 21 years in the MNC-MC group and up to 19 years in the Gran-MC group. Of MC patients alive at 10 years, MC persisted in 83% in the MNC-MC and 57% in the Gran-MC groups. In conclusion, mixed chimerism may remain stable over a very long time period. In survivors without relapse at 1 year after HSCT, determining lineage specific chimerism may be useful as outcome differs, MNC-MC being associated with better outcome than Gran-MC.