Comparison of second transplantation and donor lymphocyte infusion for donor mixed chimerism after allogeneic stem cell transplantation for nonmalignant diseases

Background Donor mixed chimerism (MC) is an increasing problem after hematopoietic stem cell transplantation (HSCT) for nonmalignant diseases. Procedure In this study, a self-administered questionnaire was used to retrospectively compare efficacy and safety in 49 patients undergoing second HSCT (n = 13) or donor lymphocyte infusion (DLI; n = 36) as treatment for MC. Results The response rate to DLI of patients with secondary graft failure (GF) (25.0%) was significantly lower than that of patients without secondary GF (81.3%; P = 0.041). Among patients undergoing DLI, the rates of successful response were significantly higher in patients having at least 30% donor chimerism (94.1%) than in patients having less than 30% donor chimerism (61.1%; P = 0.041). Furthermore, the rates of successful response were significantly higher in patients receiving larger first or maximum doses of DLI. Sixteen (50.0%) of 32 patients without secondary GF attained complete chimerism after DLI. The cumulative incidence of grade II–IV acute graft-versus-host disease and cytopenia was 37.6 and 26.1%, respectively. Conclusions DLI yields promising response rates in most patients with higher donor chimerism levels, whereas second HSCT is more likely to benefit patients with lower donor chimerism levels.