[Release of peripheral blood stem cells following chemotherapy in childhood malignancies]

Peripheral blood stem cells released following chemotherapy were examined in 21 children with malignancies in early remission. In order to obtain more than 1 x 10(5) CFU-GM per liter which is the minimal concentration to achieve autologous blood stem cell transplantation by cytapheresis, myelosuppressive chemotherapy which reduced leukocyte count below 1,000/microliters or neutrophil count below 200/microliters was necessary. Because the repetition of chemotherapy reduced the release of CFU-GM in peripheral blood, blood stem cells should be collected early after the beginning of chemotherapy. By long term culture method, peripheral blood stem cells seemed to contain pluripotent stem cells. Using our therapeutic protocol, more than 1 x 10(5) CFU-GM per liter could be obtained in malignant lymphoma and acute non-lymphoblastic leukemia, thus autologous blood stem cell transplantation seemed to be possible in these diseases.