title: Clonality analysis after retroviral-mediated gene transfer to CD34+ cells from the cord blood of ADA-deficient SCID neonates.
abstract: A clinical trial of retroviral-mediated transfer of the adenosine deaminase (ADA) gene into umbilical cord blood CD34(+) cells was started in 1993. ADA-containing peripheral blood mononuclear cells (PBMCs) have persisted in patients from this trial, with T lymphocytes showing the highest prevalence of gene marking. To gain a greater understanding of the nature and number of the transduced cells that were engrafted, we used linear amplification-mediated PCR (LAM-PCR) to identify clonal vector proviral integrants. In one patient, a single vector integrant was predominant in T lymphocytes at a stable level over most of the eight-year time span analyzed and was also detected in some myeloid samples. T-cell clones with the predominant integrant, isolated after eight years, showed multiple patterns of T-cell receptor (TCR) gene rearrangement, indicating that a single pre-thymic stem or progenitor cell served as the source of the majority of the gene-marked cells over an extended period of time. It is important to distinguish the stable pattern of monoclonal gene marking that we observed here from the progressive increase of a T-cell clone with monoclonal gene marking that results from leukemic transformation, as observed in two subjects in a clinical trial of gene therapy for X-linked severe combined immunodeficiency (SCID).
authors.affiliation: Department I of Internal Medicine, University of Freiburg, Freiburg, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Schmidt
authors.forename: Denise A
authors.initials: DA
authors.lastname: Carbonaro
authors.forename: Carsten
authors.initials: C
authors.lastname: Speckmann
authors.forename: Manuela
authors.initials: M
authors.lastname: Wissler
authors.forename: John
authors.initials: J
authors.lastname: Bohnsack
authors.forename: Melissa
authors.initials: M
authors.lastname: Elder
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Aronow
authors.forename: Jan A
authors.initials: JA
authors.lastname: Nolta
authors.forename: Donald B
authors.initials: DB
authors.lastname: Kohn
authors.forename: Christof
authors.initials: C
authors.lastname: von Kalle
mesh_terms: D000243:Adenosine Deaminase / Q000235:genetics*; D018952:Antigens, CD34; D002999:Clone Cells; D005312:Fetal Blood; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006801:Humans; D007231:Infant, Newborn; D016133:Polymerase Chain Reaction; D012190:Retroviridae / Q000235:genetics; D016511:Severe Combined Immunodeficiency / Q000628:therapy*; D013601:T-Lymphocytes / Q000378:metabolism; D014161:Transduction, Genetic
chemical_list: D018952:Antigens, CD34; D000243:Adenosine Deaminase