Growth factor receptor profile of CD34⁺ cells in normal bone marrow, cord blood and mobilized peripheral blood

Abstract

Growth factors regulate the proliferation and differentiation of hemopoietic cells. Their effect on hemopoietic precursors differs according to the ontogenic source of the cells. Cord blood and mobilized blood CD34(+) cells have a higher sensitivity for growth factors than bone marrow CD34(+) cells. This could be due to a higher expression of growth factor receptors. Therefore, we examined the expression of receptors for stem cell factor (SCF), interleukin-6 (IL-6), IL-3, granulocyte colony-stimulating factor (G-CSF) and IL-7 on the CD34(+) cells of cord blood, mobilized peripheral blood and bone marrow. The receptors were detected with monoclonal antibodies and flow cytometry. The majority of the CD34(+) cells in bone marrow clearly expressed SCFR; they showed a moderate positivity for IL-3Ralpha and a weak staining for G-CSFR and IL-6 Ralpha. Less than 10% of the cells were IL-7R positive. Cord blood CD34(+) cells showed a higher expression of SCFR and a lower positivity for G-CSFR and IL-6Ralpha. Mobilized blood CD34(+) cells showed a lower expression of SCFR and G-CSFR, and a higher positivity for IL-3Ralpha. This was not solely due to the presence of more myeloid precursors in mobilized blood, as the growth factor receptor profile did not correspond to that of early or late myeloid CD34(+) precursors in normal bone marrow. Changes induced by the mobilization procedure occurred as well. In conclusion, the higher sensitivity for growth factors of hemopoietic precursors in cord blood and mobilized blood cannot be explained by a general increase of the growth factor receptor expression on the CD34(+) cells.

A novel function of granulocyte colony‐stimulating factor in mobilization of human hematopoietic progenitor cells

“…We first detected the expression of G‐CSFR on the cells that had migrated into the lower chamber. The results showed the positive percentage of G‐CSFR expression on CD34 + cells was 49.8%, which was similar to that observed in a previous study, 15 and among G‐CSFR positive cells the percentage of CD34 was 86.3% (Figure 1b). Interestingly, only half of the outcome cells expressed G‐CSFR, which suggested indirect effect of G‐CSF existed or CD34 − cells such as monocytes or neutrophils transmigrating toward G‐CSF accompanied by HPC adhered to themselves.…”

Multilevel Regulation of IL‐6R by IL‐6–sIL‐6R Fusion Protein According to the Primitiveness of Peripheral Blood‐Derived CD133+Cells

“…Numerous studies have been performed to determine the expression of mIL‐6R on the surface of HSCs, but results are contentious and diverge greatly from 20%–90% according the HSC model used by the authors [1, 3, 12–15, 23, 42]. However, to our knowledge, no experiment has so far been carried out to study mIL‐6R expression in the model of 5‐FU‐selected CD133 + cells described herein.…”

Phenotypic and functional characteristics of CD34+ cells are related to their anatomical environment: is their versatility a prerequisite for their bio-availability?

“…Concerning the expression of hematopoietic-related cytokine receptors, the marked difference of IL-3R, EpoR, and G-CSFR␣ expressions observed between SSPB and SSBM CD34 ϩ cells may explain, at least partially, their differential BFU-E and CFU-GM clonogenicity [18]. The higher expression of receptors to inflammatory cytokines such as IFN-R␣/IFN-R␤, TNF-RI/TNF-RII, and CCR1 on SSPB, as compared with SSBM CD34 ϩ cells, tallies with the need for a rapid mobilization to the inflammation sites where their ligands are produced.…”