Identification and cloning of a prethymic precursor T lymphocyte from a population of common acute lymphoblastic leukemia antigen (CALLA)-positive fetal bone marrow cells.
We have cloned common acute lymphoblastic leukemia (CALLA)-positive cells from human fetal bone marrow containing less than 1 in 10,000 E-RFC in round-bottomed microtiter wells (one cell per well) using the autocloning unit of an EPICS-V cell sorter. Expansion of such cells (with IL-2 and heavily irradiated autologous thymocytes as feeder cells) resulted in growth in 6-14% of the wells (mean, 11%) with cells with mature T lymphocyte phenotype. Two-color fluorescence analysis of outgrowing cultures furthermore ascertained that these cells had differentiated through a phase of simultaneous expression of T4 and T8 antigens and at the same time expression of the thymocyte-associated T6 antigens. Thus, given the fact that 10-20% of T cell acute lymphoblastic leukemia (T-ALLs) are CALLA+, we have been able to identify a human prethymic T lymphocyte population that might be the normal counterpart of precursor cell to the CALLA+ T-ALL cell.
D000945:Antigens, Differentiation, T-Lymphocyte; D000951:Antigens, Neoplasm / Q000032:analysis*; D000954:Antigens, Surface / Q000032:analysis; D001853:Bone Marrow / Q000276:immunology*; D002999:Clone Cells; D004253:DNA Nucleotidylexotransferase / Q000032:analysis; D005333:Fetus / Q000276:immunology; D006412:Hematopoietic Stem Cells / Q000276:immunology*; D006801:Humans; D015260:Neprilysin; D013601:T-Lymphocytes / Q000276:immunology*
D000945:Antigens, Differentiation, T-Lymphocyte; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D004253:DNA Nucleotidylexotransferase; D015260:Neprilysin