Phenotypic characteristics of cord blood hemopoietic cells.

Bone marrow transplantation is limited due to the lack of HLA-matched donors and to the frequent occurrence of GvHD. Hemopoietic transplants using cord blood cells are being increasingly used in pediatric patients. In this study, the immunophenotypic characteristics of cord blood cells have been investigated by one or two-color flow cytometric analysis. The CB cells were characterized by a low proportion of CD3+ T-cells, increased CD4/CD8 and CD45RA/CD45RO ratios, minimal expression of HLA-DR, increased proportion of CD5CD19 double positive B-cells, while CD3- CD8+ and CD3- CD7+ subsets, not usually found in adult PB, were detected. These data reflect the immaturity of CB cells as assessed by immunophenotypic analysis suggesting that it could be a valuable alternative source of transplantable hematopoietic progenitor cells and might alleviate some of the problems associated with bone marrow or peripheral blood transplantation.

Mutations of retinoblastoma gene (Rb-1) as a prognostic factor in children with acute leukemia and neuroblastoma.

Rb-1 is a tumor suppressor gene encoding for a nuclear phosphoprotein acting as a cell cycle regulator, normally expressed in hematopoietic cells and more often inactivated by point mutations with predominance for exons 20-24. The aim of this study is to correlate the retinoblastoma-1 (Rb-1) gene mutations with the prognosis and progression of childhood acute leukemia and neuroblastoma. Bone marrow slides from 26 children with leukemia (18 acute lymphoblastic leukemia [ALL] and 8 acute myeloid leukemia [AML]) and 4 children with neuroblastoma were studied. Exons 20, 21, and 22 were amplified using the polymerase chain reaction technique. Single strand conformational polymorphism (SSCP) and heterodoublex analysis were performed to detect mutations. In ALL cases, two samples in exon 20 (11.11%), one in exon 21 (5.56%), and four in exon 22 (22.22%) had altered conformation. All but one of these cases were classified as high-risk leukemia patients who either relapsed or never achieved remission. Two of the AML cases who did not achieve remission and one of the neuroblastoma cases with concomitant bone marrow infiltration had altered conformation as well. The SSCP and heterodoublex analysis showed that all but one who did not belong to the high-risk group had the same altered conformation. These data suggest that Rb-1 gene could possibly be used as an independent prognostic factor for the acute leukemia of childhood and result in the intensification of chemotherapy. In solid tumors with bone marrow involvement it could play a role as a marker of aggressive disease.