T Kikuchi

Publications (2)7.86 Total impact

• Article: Megakaryocytes derived from CD34-positive cord blood cells produce interleukin-8.

  T Higuchi, K Koike, N Sawai, H H Mwamtemi, K Takeuchi, M Shiohara, T Kikuchi, K Yasui, S Ito, O Yamagami, Y Sasaki, N Okumura, T Kato, H Miyazaki, M Ikeda, M Yamada, A Komiyama
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  ABSTRACT: In a serum-free liquid culture, thrombopoietin (TPO) selectively stimulated the growth of megakaryocytic cells from CD34-positive cord blood cells. Using these cultured cells, we investigated cytokine production by human megakaryocytes. Day 10 megakaryocytes (2 x 10(5)) secreted > 1000 pg/ml of interleukin (IL)-8, in contrast to small amounts of IL-1beta and IL-6. A time-course study showed that the IL-8 production of megakaryocytes occurred at the late phase of the culture period. The megakaryocyte-conditioned medium had the chemotactic potential of polymorphonuclear leucocytes, which was abrogated by the addition of anti-IL-8 antibody, suggesting the secretion of biologically active IL-8. The combination of TPO and IL-1alpha was required for a significant augmentation of the IL-8 secretion. Direct evidence for IL-8 synthesis in megakaryocytes was provided by reverse transcription-polymerase chain reaction on purified CD41b+ cells and by the detection of intracellular IL-8 in CD41b+ cells. These results suggest that TPO stimulates not only the proliferation and differentiation of the progenitors capable of megakaryocytic lineage expression but also IL-8 release by the megakaryocytic cells with the aid of IL-1.
  British Journal of Haematology 12/1997; 99(3):509-16. · 4.94 Impact Factor
• Article: Analysis of synergism between stem cell factor and granulocyte-macrophage colony-stimulating factor on human megakaryoblastic cells: an increase in tyrosine phosphorylation of 145 kDa subunit of c-kit in two-factor combination.

  T Kamijo, K Koike, K Takeuchi, T Higuchi, N Sawai, T Kikuchi, H Tsumura, H Akiyama, T Koike, E Ishii, A Komiyama
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  ABSTRACT: In normal hematopoiesis, stem cell factor (SCF) stimulates survival, proliferation and differentiation of hematopoietic progenitors. Although SCF acts synergistically with a variety of cytokines, the mechanism of growth factor-cooperation remains to be determined. To analyze the synergism between SCF and granulocyte-macrophage colony-stimulating factor (GM-CSF), we established a new megakaryoblastic cell line, HML-2, by culture in the presence of both SCF and GM-CSF. While SCF alone or GM-CSF alone supported modest cell growth, SCF and GM-CSF together induced substantial growth of this cell line. SCF alone tyrosine-phosphorylated several bands including the 145 kDa subunit of c-kit. GM-CSF alone did not cause the tyrosine phosphorylation of the 145 kDa subunit, but markedly up-regulated the expression of the 145 kDa subunit of c-kit. The combination of SCF and GM-CSF resulted in a synergistic increase in tyrosine phosphorylation of the 145 kDa subunit of c-kit. Several proliferation inhibitors which removed the two-factor interaction on the growth of the HML-2 cells down-regulated the 145 kDa subunit of c-kit. Thus, a synergistic increase in tyrosine phosphorylation of the 145 kDa subunit of c-kit may be one possible mechanism underlying the cooperation of SCF and GM-CSF on the HML-2 cell growth.
  Leukemia Research 21(11-12):1097-106. · 2.92 Impact Factor