Hematopoietic and immune recovery after allogeneic peripheral blood stem cell transplantation and bone marrow transplantation in a pediatric population.

Abstract

To compare the hematopoietic and immune recoveries after allogeneic transplantation with different cell sources, we analyzed the recovery patterns of blood components after allogeneic peripheral blood stem cell transplantation (PBSCT) in comparison with that after allogeneic bone marrow transplantation (BMT) in a pediatric population. Sixteen patients received PBSCT, and 24 received BMT between January, 1995 and March, 2000. The patients had acute lymphoblastic leukemia (ALL; n = 22), acute myelogenous leukemia (AML; n = 8), myelodysplastic syndrome (MDS; n = 3), or other diseases (n = 7). The median ages of patients in the PBSCT and BMT groups were 9 yr and 6 yr, respectively. Cyclosporin A (CsA) plus methotrexate or methylprednisolone was used as a graft-vs.-host disease (GvHD) prophylaxis regimen in the PBSCT group, whereas CsA alone or methotrexate alone was used in the BMT group. Circulating lymphocyte numbers and subpopulations determined by flow cytometric analysis were used as markers of immune recovery. In the PBSCT group, the median number of harvested CD34+ cells was 7.25 (range: 1.3-27.6) x 106/kg of the recipient's body weight, while the median number of harvested nucleated cells was 4.7 (range: 3.7-10.5) x 108/kg. All of the patients were engrafted. Myeloid engraftment occurred sooner after PBSCT than after BMT (median number of days to achieve absolute neutrophil counts (ANC) > 0.5 x 109/L; 11 and 15, respectively; p < 0.0001) and similar results were found for platelet engraftment (median number of days to achieve a platelet count of > 20 x 109/L; 12 and 21, respectively; p = 0.004). On the other hand, after PBSCT the absolute numbers of total circulating lymphocytes and lymphocyte subpopulations were not significantly different from those after BMT. The incidence of acute GvHD after PBSCT was the same as that after BMT, while chronic GvHD developed more frequently after PBSCT than after BMT (p = 0.005). In a pediatric population, the indications for PBSCT and BMT should be based on these findings in addition to regard for the donor's safety.