Flt3/Flk-2 and c-Kit are not essential for the proliferation of B lymphoid progenitor cells in the bone marrow of the adult mouse.
The receptor tyrosine kinase Flk-2/Flt3 was originally cloned from hematopoietic stem cell-enriched fetal liver and placenta and is believed by some investigators to play a role in the regulation of the hematopoietic stem cell. However, targeted disruption of the flt3 gene results in a specific deficiency in early B cell progenitors. Using an antagonistic monoclonal antibody developed against the extracellular domain of Flt3, we investigated the expression and function of the molecule on B lymphoid lineage cells in the bone marrow (BM) of adult mice. Approximately 10% of B220+ cells in the BM expressed Flt3 on the cell surface, and most of the cells belonged to a pro-B cell fraction when judged by an expression pattern of CD43, heat-stable antigen, and BP-1. However, B lymphoid precursor cells that are clonable in vitro could not be enriched in the B220+/Flt3+ cell fraction sorted by flow cytometry. Furthermore, proliferation of B lymphoid precursor cells in the adult BM was not blocked by administration of the antagonistic monoclonal antibodies against Flt3 and c-Kit, suggesting that signalings mediated by Flt3 and c-Kit receptors are not essential for the proliferation of B cell progenitors in adult mouse BM.
Ogawa
M
M
Department of Molecular Genetics, Faculty of Medicine, Kyoto University, Japan.
Sugawara
S
S
Kunisada
T
T
Sudo
T
T
Hayashi
S
S
Nishikawa
S
S
Kodama
H
H
Nishikawa
S
S
D000818:Animals; D001402:B-Lymphocytes / Q000473:pathology* / Q000502:physiology*; D001853:Bone Marrow / Q000502:physiology; D002454:Cell Differentiation; D002455:Cell Division; D019070:Cell Lineage; D005260:Female; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D019009:Proto-Oncogene Proteins c-kit / Q000502:physiology*; D020794:Receptor Protein-Tyrosine Kinases / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology; D019089:Stem Cell Factor / Q000502:physiology; D051941:fms-Like Tyrosine Kinase 3
D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D019089:Stem Cell Factor; C084881:flt3 ligand protein; C497971:Flt3 protein, mouse; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3