Transplantation of highly purified peripheral blood CD34(+) cells from HLA-mismatched parental donors in 14 children: evaluation of early monitoring of engraftment

HLA-mismatched family members may represent an important cell source for pa tients that require stem cell transplantation but lack both a matched sibli ng donor and a closely matched unrelated donor. We report the outcome of 19 transplantations from HLA two- or three- loci mismatched parental donors i n which 14 pediatric patients with hematological malignancies or other diso rders, received a median of 21.5 x 10(6) (range, 5.4-58) highly purified CD 34(+) peripheral blood stem cells (PBSC), as well as 4.7 x 10(4) (range, 0. 4-12) donor T cells per kg body weight. T cell depletion was performed usin g a two-step CD34-positive selection on two different magnetic beads device s. Ten of 14 patients presented with rapid myeloid engraftment. The four pa tients who presented with graft failure (two non-engraftments, two rejectio ns) received a second stem cell graft and one a third. Graft rejection was detected early by polymerase chain reaction (PCR) analysis of FAGS-sorted T cells. Eight of the 14 patients are still alive after a median observation period of 15.6 months (range, 3-31.3) with full donor chimerism in all hem atopoietic cell lineages. No acute organ graft-versus-host disease (GVHD) a nd no chronic GVHD have occurred. One patient experienced relapse of leukem ia. We conclude that transplantation of allogeneic PBSC from haploidentical donors will open new perspectives for pediatric patients far whom an HLA-m atched stem cell graft is not available. Close monitoring of recipient and donor hematopoiesis might be of clinical value, to recognize early engraftm ent or rejection.