1. ¹Department of Hematology and Oncology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
2. ²Department of Hematology, Hakodate Municipal Hospital, Hakodate, Japan
3. ³Third Department of Internal Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
4. ⁴Department of Hematology, Asahikawa Municipal Hospital, Asahikawa, Japan
5. ⁵Department of Hematology, Sapporo Hokuyu Hospital, Sapporo, Japan

Correspondence: Dr J Tanaka, Department of Hematology and Oncology, Hokkaido University Graduate School of Medicine, N15 W7, Kita-Ku, Sapporo 060-8638, Japan. E-mail: jutanaka@med.hokudai.ac.jp

Received 25 October 2005; Revised 7 February 2006; Accepted 8 February 2006; Published online 20 March 2006.

Abstract

We analyzed donor-type chimerism in CD3+, CD14.15+ and CD56+ cells from 36 patients who had undergone conventional-intensity allogeneic stem cell transplantation (CST) and 34 patients who had undergone nonmyeloablative allogeneic stem cell transplantation (NST) for hematological malignancies. On day 28 after transplantation, all fractions in NST patients and CD3+ cells in CST patients who received a non-total body irradiation (TBI) regimen showed more frequent mixed chimerism (<90% donor cells) than those in patients who had received TBI. NST patients with acute graft-versus-host disease (grade II–IV) frequently showed more than 50% donor-type chimerism in CD3+ cells on day 14 (P=0.029). NST patients with <50% donor-type chimerism on day 14 and with <90% donor-type chimerism on day 28 in CD56+ cells had significantly poor 1-year overall survival (0 vs 91%, P<0.001 and 20 vs 74%, P=0.002, respectively). Both NST and CST patients with <90% donor-type chimerism in CD14.15+ cells on day 28 had significantly poor 1-year overall survival (14 vs 70%, P=0.005 and 0 vs 66%, P=0.002, respectively). Our data show that the extent of donor-type chimerism in lineage-specific cells appears to have an impact on outcome after allogeneic stem cell transplantation.