Megakaryocytes derived from CD34‐positive cord blood cells produce interleukin‐8

Abstract

Summary. 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 × 10 5 ) secreted > 1000 pg/ml of interleukin (IL)-8, in contrast to small amounts of IL-1b 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 megakaryocyteconditioned 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-1a 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 þ cells and by the detection of intracellular IL-8 in CD41b þ 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.

IL-8 and its CXCR1 and CXCR2 receptors participate in the control of megakaryocytic proliferation, differentiation, and ploidy in myeloid metaplasia with myelofibrosis

“…Our results showing that CD34 ϩ and megakaryocytically derived CD34 ϩ cells from unmobilized normal blood or from patients with MMM expressed IL-8 protein, reinforce recent data reporting IL-8 production by CD34 ϩ cells and MK cells derived from cord blood or BM. 45,46 IL-8 is known to also be produced by BM stromal and endothelial cells. Since myeloproliferation is associated with myelofibrosis and neoangiogenesis, the participation of stromal and endothelial cells in the elevated serum IL-8 level observed in MMM cannot be excluded.…”

STI571 inhibits growth and adhesion of human mast cells in culture

“…Serum-deprived liquid cultures were carried out in 24-well culture plates (#3047; Becton Dickinson) using a modification of the technique described previously [22][23][24]. To examine the effects of STI571 on the SCF-dependent development of mast cells, we used 10-week cultured cells grown with 20 ng/mL of SCF from CD34 ϩ cord blood cells as target cells, because a large number of such cultured cells were positive for tryptase, as described previously [22,23].…”

Dynamic DNA methylation change in the CpG island region of p15 during human myeloid development

“…For assaying the intracellular p15 expression of leukemic cell lines, cord blood CD34 + cells and the cultured cells generated with GM-CSF or GM-CSF + SCF, the cells were fixed and subsequently permeabilized, using Dako IntraStain (DAKO A/S), as described previously (15). The cells were incubated with 5 µl of antip15 mAb for 30 minutes at room temperature.…”