title: Phenotypic characterization of immature lymphoid cells in human umbilical cord blood.
abstract: The antigenic phenotype of neonatal lymphoid cells isolated from umbilical cord blood was investigated using monoclonal antibodies and flow cytometry. Although the majority of cells expressed mature T or B cell differentiation antigens, small subpopulations of phenotypically immature lymphocytes were detected. A small proportion (mean 2.8%) of cells expressed the common acute lymphoblastic leukaemia antigen (CD-10), a significantly higher figure than that detected on adult peripheral blood lymphocytes. The cortical thymocyte antigen (CD-1) was detected on a very small subset of cord lymphoid cells, but was also present on adult lymphocytes at approximately the same frequency. The nuclear enzyme terminal deoxynucleotidyl transferase (TdT), a marker of early lymphoid differentiation, was detected by immunofluorescence on 0.031% of mononuclear cells in cytocentrifuge preparations, representing an approximate 10-fold increase in frequency over expression in childhood or adult blood. These circulating TdT+ cells were shown in double labelling experiments to predominantly express markers of B cell differentiation (CD-24, CD-10, MHC Class 2), although occasional cells co-expressing the T lineage marker CD-2 were also seen. These findings are consistent with the circulation of B cell precursors in neonatal blood. The nature of the CD-1+ cells is unclear, although the absence of CD-1+ TdT+ double labelled cells mitigates against the possible presence of immature thymus-processed lymphocytes in these samples.
authors: Haematology Department, Institute of Clinical Pathology and Medical Research, Westmead Hospital, NSW, Australia.
authors: K F
authors: KF
authors: Bradstock
authors: A
authors: A
authors: Kerr
authors: P
authors: P
authors: Grimsley
authors: J
authors: J
authors: Kirk
authors: C
authors: C
authors: Luxford
mesh_terms: D000328:Adult; D018949:Antigens, CD1; D000943:Antigens, Differentiation; D002454:Cell Differentiation; D004253:DNA Nucleotidylexotransferase / Q000378:metabolism; D005312:Fetal Blood / Q000166:cytology*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000201:enzymology / Q000276:immunology; D006801:Humans; D008214:Lymphocytes / Q000145:classification / Q000166:cytology / Q000201:enzymology / Q000276:immunology*; D010641:Phenotype
chemical_list: D018949:Antigens, CD1; D000943:Antigens, Differentiation; D004253:DNA Nucleotidylexotransferase