title: CD4+ T cells in aged or thymectomized recipients of allogeneic stem cell transplantations.
abstract: BACKGROUND
  CD4+CD25highFOXP3+ regulatory T (Treg) cells, which include thymus-derived and peripherally induced cells, play a central role in immune regulation, and are therefore crucial to prevent graft-versus-host disease (GVHD). The increasing use of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for elderly patients with thymus regression, and our case of allo-HSCT shortly after total thymectomy, raised questions about the activity of thymus-derived Treg cells and peripherally induced Treg cells, which are otherwise indistinguishable.
  
  
  RESULTS
  We found that despite pre-transplant thymectomy or older age, both naïve and effector Treg cells, as well as naïve and effector conventional T cells, proliferated in allo-HSCT recipients. Higher proportions of total Treg cells 1 month post allo-HSCT, and naïve Treg cells 1 year post allo-HSCT, appeared in patients achieving complete chimera without developing significant chronic GVHD, including our thymectomized patient, compared with patients who developed chronic GVHD.
  
  
  CONCLUSIONS
  Treg cells that modulate human allogeneic immunity may arise peripherally as well as in the thymus of allo-HSCT recipients.
authors.affiliation: Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima, Japan. hiroc@fmu.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima, Japan. kazu-ike@fmu.ac.jp.|Department of Blood Transfusion and Transplantation Immunology, School of Medicine, Fukushima Medical University, 1 Hikariga-oka, Fukushima, Fukushima, 960-1295, Japan. kazu-ike@fmu.ac.jp.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ikeda
authors.affiliation: Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima, Japan. kogawa@fmu.ac.jp.
authors.forename: Kazuei
authors.initials: K
authors.lastname: Ogawa
authors.affiliation: Department of Blood Transfusion and Transplantation Immunology, School of Medicine, Fukushima Medical University, 1 Hikariga-oka, Fukushima, Fukushima, 960-1295, Japan. s-saitou@fmu.ac.jp.
authors.forename: Syunnichi
authors.initials: S
authors.lastname: Saito
authors.affiliation: Department of Blood Transfusion and Transplantation Immunology, School of Medicine, Fukushima Medical University, 1 Hikariga-oka, Fukushima, Fukushima, 960-1295, Japan. doc_mayindu@yahoo.fr.|Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, QC, Canada. doc_mayindu@yahoo.fr.
authors.forename: Alain M
authors.initials: AM
authors.lastname: Ngoma
authors.affiliation: Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima, Japan. hidebone@fmu.ac.jp.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Mashimo
authors.affiliation: Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima, Japan. kouki@fmu.ac.jp.
authors.forename: Koki
authors.initials: K
authors.lastname: Ueda
authors.affiliation: Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima, Japan. mikifuru@fmu.ac.jp.
authors.forename: Miki
authors.initials: M
authors.lastname: Furukawa
authors.affiliation: Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima, Japan. accon@fmu.ac.jp.
authors.forename: Akiko
authors.initials: A
authors.lastname: Shichishima-Nakamura
authors.affiliation: Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima, Japan. ohkawara@fmu.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohkawara
authors.affiliation: Department of Blood Transfusion and Transplantation Immunology, School of Medicine, Fukushima Medical University, 1 Hikariga-oka, Fukushima, Fukushima, 960-1295, Japan. nollet@fmu.ac.jp.
authors.forename: Kenneth E
authors.initials: KE
authors.lastname: Nollet
authors.affiliation: Department of Blood Transfusion and Transplantation Immunology, School of Medicine, Fukushima Medical University, 1 Hikariga-oka, Fukushima, Fukushima, 960-1295, Japan. hit-ohto@fmu.ac.jp.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ohto
authors.affiliation: Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima, Japan. takeishi@fmu.ac.jp.
authors.forename: Yasuchika
authors.initials: Y
authors.lastname: Takeishi
mesh_terms: D000328:Adult; D000367:Age Factors; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D005260:Female; D006086:Graft vs Host Disease / Q000276:immunology / Q000517:prevention & control*; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D013934:Thymectomy; D014184:Transplantation, Homologous; D055815:Young Adult