Soluble interleukin-6 (IL-6) receptor with IL-6 stimulates megakaryopoiesis from human CD34+ cells through glycoprotein (gp) 130 signaling

摘要: We have recently shown that stimulation of glycoprotein (gp) 130, the membrane-anchored signal transducing receptor component IL-6, by a complex human soluble interleukin-6 (sIL-6R) and IL-6 (sIL-6R/IL-6), potently stimulates ex vivo expansion as well erythropoiesis stem/progenitor cells in presence stem cell factor (SCF). Here we show sIL-6R dose-dependently enhanced generation megakaryocytes (Mks) (IIbIIIa-positive cells) from CD34+ serum-free suspension culture supplemented with SCF. The sIL-6R/IL-6 also synergistically acted IL-3 thrombopoietin (TPO) on Mks cells, whereas synergy alone TPO was barely detectable. Accordingly, addition to combination SCF + supported substantial number Mk colonies methylcellulose culture, absence rarely induced colonies. monoclonal antibodies against gp130 clonal cultures completely abrogated megakaryopoiesis SCF, an anti-TPO antibody did not, indicating observed is response signaling independent TPO. Furthermore, were subfractionated into two populations IL-6R–negative (CD34+ IL-6R−) IL-6R–positive IL-6R+) fluorescence-activated sorting. CD34+IL-6R− produced or In contrast, IL-6R+cells generated much less lacked colony forming activity under same conditions. Collectively, present results indicate most progenitors do not express IL-6R, confers responsiveness IL-6. Together functional serum relative unresponsiveness vitro, current suggest role may be mainly mediated sIL-6R, initiated sIL-6R/ involved vivo.