Analysis of interleukin 6 receptor and gp130 expressions and proliferative capability of human CD34+ cells.

Abstract

SummaryWe recently demonstrated that stimulation of gp 130 by a combination of soluble interleukin 6 receptor (slL-6R) and IL-6 but not IL-6 alone significantly stimulates the ex vivo expansion of primitive hematopoietic progenitors and the generation of erythroid cells from human CD34 + cells in the presence of stem cell factor (SCF). Here, we show that gp130 is found low positively on most CD34 + cells, whereas IL-6R is expressed on only 30-50% of these cells. Although most of the colonies generated from FACS| CD34+IL-6R + cells were granulocyte/macrophage (GM) colonies, CD34+IL-6R -cells gave rise to various types of colonies, including erythroid bursts, GM, megakaryocytes, and mixed colonies in methylcellulose culture with a combination of IL-6, slL-6R, and SCF. Similar results were obtained in culture supplemented with a combination of IL-3, IL-6, SCF, granulocyte colony-stimulating factor, erythropoietin, and thrombopoietin. A limiting dilution analysis of long-term culture-initiating cells (LTC-IC) showed that the CD34+IL-6P, -cells contained a larger number of LTC-IC than did the CD34+IL-6R + cells. In a serum-free suspension ofCD34+IL-61:( -cells, the addition of slL-6P, to the combination oflL-6 and SCF dramatically increased the total and multipotential progenitors, whereas CD34+IL-6R. + cells failed to do so under the same conditions. These results indicate that most of the erythroid, megakaryocytic, and primitive human hematopoietic progenitors are included in the IL-61:(-populations, and the activation of gp130 on these progenitors can be achieved by a complex of IL-6-slL-6R, but not by IL-6 alone. The present culture system using IL-6, slL-6R., and SCF may provide a novel approach for ex vivo expansion of human primitive hematopoietic progenitors.

Gp130-Signaling synergizes with FL and TPO for the long-term expansion of cord blood progenitors

“…In their study, the IL-6/ sIL-6R complex stimulated in particular the expansion of erythroid and mixed colonies, while the number of CFU-GM was similar in the cultures supplemented with either IL-6 or the IL-6/sIL-6R complex. This is in line with the findings of Tajima et al, 32 who showed that erythroid progenitors and CFU-GEMM segregate with the CD34 …”

“…32,35,36 Similar results have been obtained using a combination of IL-6, sIL-6R and FL although the synergistic action was weaker than with SCF. 37 Recently, the complex of IL-6 and sIL-6R has also been shown to stimulate megakaryopoiesis in the presence of SCF or IL-3 and TPO.…”

“…32,33 These CD34 + IL-6R␣ + cells are predominantly myeloid precursors. In contrast, erythroid and megakaryocytic progenitors as well as long-term culture initiating cells (LTC-IC) have been found to be enriched in the CD34 + IL-6R␣ − UCB fraction and to lack responsiveness to IL-6.…”

“…In contrast, erythroid and megakaryocytic progenitors as well as long-term culture initiating cells (LTC-IC) have been found to be enriched in the CD34 + IL-6R␣ − UCB fraction and to lack responsiveness to IL-6. 32 However, a soluble form of IL-6R␣ (sIL-6R) has been shown to complex with IL-6 and to act agonistically on gp130 + IL-6R␣ − cells.…”

Mechanisms Mediating the Inhibitory Effect of All‐Trans Retinoic Acid on Primitive Hematopoietic Stem Cells in Human Long‐Term Bone Marrow Culture

“…The common transducing signal chain gp130, for all receptors of the IL-6 cytokine family including IL-6, IL-11, oncostatin M, leukemia inhibitory factor, ciliary neurotrophic factor, and cardiotrophin, is homodimerized by both IL-6 and IL-11 in murine bone marrow stroma [24]. gp130 is expressed in most primitive human hemopoietic CD34 + cells [25], and its signaling was shown in numerous studies to synergize with other hemopoietic cytokines to stimulate trilineage human hemopoiesis and expand primitive human hemopoietic stem cells [26][27][28][29][30][31][32]. Also, the addition of anti-gp130 monoclonal antibodies completely abrogated the synergistic action [26][27][28][29][30].…”