Abstract: Objective  To investigate the relationship between chimerism and leukemia relapse after allogeneic hematopoietic stem cell transplantation(allo HSCT). Methods  Totally 73 adults with leukemia undergoing  myeloablative  allo HSCT  from January 2014 to June 2018 were retrospectively analyzed.  Polymerase chain reaction amplification of short tandem repeat sequence（STRPCR） was used to detect donor cell chimerism rates of recipient bone morrow after +30 d, +60 d,+90 d of transplantation. Then the relationship between  chimerism and the relapse was analyzed.Results  Thechimerism rate of the relapse group was lower than that of non-relapsegroup after +90 d of transplantation. Patients with low chimerism had higher relapse rate after +60 d and +90 d of transplantation（P=0.021, 0.027, respectively）. Multivariate analysis showed that leukemia status before  transplantation, donor cell chimerismrate  after  +60 days of  transplantation, donor cell chimerismrate after +90 days of transplantation were the risk factors of relapse after patients undergoing allo HSCT. Conclusion  The study indicated that chimerismrate has predictive value for leukemia recurrence afterallo HSCT. And the recurrence rate of patients with low chimerism after +60 d and +90 d  of transplantation is high.

Key words: leukemia； hematopoietic , stem , cell , transplantation；chimerism； relapse