1. ¹Department of Hematology and Oncology, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
2. ²Hematopoietic Cell Transplantation Team, Tokyo Metropolitan Komagome Hospital, Bunkyo-ku, Tokyo, Japan
3. ³Department of Hematology and Oncology, Graduate School of Medicine, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan

Correspondence: Dr K Haraguchi, Department of Hematology and Oncology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. E-mail: kyoh-tky@umin.ac.jp

⁴Hisamaru Hirai died on August 23, 2003, during the preparation of this manuscript.

Received 9 January 2004; Accepted 14 April 2004; Published online 9 August 2004.

Abstract

Human V24⁺ natural killer T (NKT) cells have an invariant T-cell receptor- chain and are activated in a CD1d-restricted manner. V24⁺ NKT cells are thought to regulate immune responses and to play important roles in the induction of allograft tolerance. In this report, we analyzed the recovery of V24⁺ NKT cells after hematopoietic stem cell transplantation and its correlation with graft-versus-host disease (GVHD). Patients who received a dose-reduced conditioning regimen, antithymocyte globulin- or CAMPATH-1H-containing conditioning regimen were excluded. NKT cells were reconstituted within 1 month after transplantation in peripheral blood stem cell transplantation recipients, while their numbers remained low for more than 1 year in bone marrow transplantation (BMT) recipients. The number of V24⁺ NKT cells in BMT recipients with acute GVHD was lower than that in patients without acute GVHD, and both the CD4⁺ and CD4^- V24⁺ NKT subsets were significantly reduced. With regard to chronic GVHD, BMT recipients with extensive GVHD had significantly fewer V24⁺ NKT cells than other patients. Furthermore, the number of CD4⁺ V24⁺ NKT cells was also significantly reduced in patients with chronic extensive GVHD. Our results raise the possibility that the number of V24⁺ NKT cells could be related to the development of GVHD.