Functional and phenotypic characterization of cord blood and bone marrow subsets expressing FLT3 (CD135) receptor tyrosine kinase

摘要: The class III receptor tyrosine kinase FLT3/FLK2 (FLT3; CD135) represents an important molecule involved in early steps of hematopoiesis. Here we compare cell-surface expression FLT3 on bone marrow (BM) and cord blood (CB) cells using monoclonal antibodies (MoAbs) specific for the extracellular domain human FLT3. Flow cytometric analysis MACS-purified BM CB showed that 63% to 82% CD34+ 88% 95% coexpress Clonogenic assays morphological characterization FACS-sorted demonstrate colony-forming unit–granulocyte-macrophage (CFU-GM) immature myelo-monocytic precursor are enriched subpopulation staining most brightly with MoAb whereas majority burst-forming units-erythroid (BTU-E) small lymphoid morphology found FLT3− population. In contrast, statistically indistinguishable proportions CFU-granulocyte-erythrocyte-megakaryocyte-macrophage (CFU-GEMM) more primitive cobblestone area forming (CAFC) were detected both fractions, albeit FLT3+ fraction consistently CAFC activity than fraction. Although both, CD34+CD117+ (KIT+), CD34+CD90+ (Thy-1+), CD34+CD109+ FLT3, three-color phenotypic analyses consistent functional findings suggest defined as CD34+CD38−, CD34+CD71low, CD34+HLA-DR−, CD34+CD117low, CD34+CD90+, express low levels therefore not a significant extent bright versus negative sorting scheme. Thus, clear segregation progenitors from was confounded by apparent these cells, myeloid unambiguously segregated brightest erythroid dimmest. Additional MoAbs against progenitor/stem cell markers including mucinlike MGC-24v (CD164), kinases TIE, FMS (CD115), KIT (CD117) further illustrate differences surface antigen profiles cells. Notably, CD115 is rarely 20% 25% CD34+FLT3+ CD115+. Furthermore, 80% but only 60% 75% Only negligible amount CD34+CD19+ CB, while 30% presumed pro/pre-B CD34+CD164+ CD34+TIE+ subsets Analysis unseparated restricted subsets. About 65% 70% lymphocyte-gated CD34−FLT3+ positive monocytic marker consist CD10 expressing B-cell precursors. Finally, CD34− monocytes BM, PB granulocytes FLT3−. Our data show detectable appears first at multilineage progenitor disappears during stages development, upregulated maintained maturation. © 1997 American Society Hematology.