Tehran University of Medical Sciences International Journal of Hematology-Oncology and Stem Cell Research 2008-2207 14 1 2020 01 01 1 10 Hitoshi Yoshida Department of Hematology , Osaka International Cancer Institute, Osaka, Japan Midori Koike Department of Hematology , Osaka International Cancer Institute, Osaka, Japan Yuma Tada Department of Hematology , Osaka International Cancer Institute, Osaka, Japan Keiichi Nakata Department of Hematology , Osaka International Cancer Institute, Osaka, Japan Akihisa Hino Department of Hematology , Osaka International Cancer Institute, Osaka, Japan Shigeo Fuji Department of Hematology , Osaka International Cancer Institute, Osaka, Japan Hiroaki Masaie Department of Hematology , Osaka International Cancer Institute, Osaka, Japan Chihiro Oka Department of Laboratory, Osaka International Cancer Institute, Osaka, Japan Akemi Higeno Department of Laboratory, Osaka International Cancer Institute, Osaka, Japan Atushi Idota Department of Laboratory, Osaka International Cancer Institute, Osaka, Japan Tomoyuki Yamasaki Department of Laboratory, Osaka International Cancer Institute, Osaka, Japan Jun Ishikawa Department of Hematology , Osaka International Cancer Institute, Osaka, Japan 2019 04 09 2019 12 07 Background: Advances of allogeneic hematopoietic cell transplantation (allo-HCT) have brought long-term survival to the patients with hematologic malignancies.  Chronic graft-versus-host disease (GVHD) is one of major problems for the long-survivors after allo-HCT.  Dysregulation of immune reconstitution has been reported to be involved in the pathogenesis of chronic GVHD.  Differences of immune reconstitution between cord blood transplantation (CBT) and unrelated bone marrow transplantation (uBMT) remain unclear in long-term survivors.  We investigated immune reconstitution in patients who survive for more than 2 years after CBT (n=21) or uBMT (n=20) without relapse of underlying disease. Materials and Methods: Using flowcytomeric analysis of peripheral blood, we investigated immune reconstitution of T cells, B cells, and NK cells between CBT and uBMT patients.  We collected clinical data regarding allo-HCT and examined the relation of immune reconstitution to the development of chronic GVHD. Results: Between CBT and uBMT patients, we found significant differences in absolute cell number of CD8+ as well as CD19+ cell and CD4/CD8 ratio even more than 2 years after allo-HCT.  Among uBMT patients, absolute cell number of naïve CD4+ cell was significantly lower in patients with chronic GVHD.  In addition, we found significant differences in absolute cell number of CD19+ cell, especially naïve B cell between patients with and without chronic GVHD in both CBT and uBMT patients.  Conclusion: These results suggest that differences of immune recovery between CBT and uBMT patients may exist even in patients who survive for more than 2 years and might be related to the development of chronic GVHD.  https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/view/1107 https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/download/1107/806