Intentional induction of mixed haematopoietic chimerism as platform for cellular therapy after HLA-matched allogeneic stem cell transplantation in childhood leukaemia patients

Allogeneic peripheral blood stem cell CD34(+)-selected transplantation followed by donor lymphocyte infusion (DLI) to maximize graft-versus-leukaemia effect while avoiding graft-versus-host disease was investigated in 22 paediatric patients with acute myeloid leukaemia (n = 10) or acute lymphoblastic leukaemia (n = 12). Patients were grafted with a median (range) 6 x 10(6) (2-31 x 10(6))/kg CD34(+) cells and 1.1 x 10(4) (0.2-3.9 x 10(4)) CD3(+) cells. Seventy-five DLI were performed with no complications. Median time (range) to neutrophil and platelet engraftment was 13 (11-15) and 12 d (8-13) respectively. Probability of relapse and disease-free survival was 23 +/- 9% and 72 +/- 6% respectively (median follow-up of 15 months).