Cytokine production by primary bone marrow megakaryocytes

Abstract

Primary human bone marrow megakaryocytes were studied for their ability to express and release cytokines potentially relevant to their proliferation and/or differentiation. The purity of the bone marrow megakaryocytes was assessed by morphologic and immunocytochemical criteria. Unstimulated marrow megakaryocytes constitutively expressed genes for interleukin-1 beta (IL-1 beta), IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-alpha (TNF-alpha), by the polymerase chain reaction (PCR) and Northern blot analysis. At the protein level, megakaryocytes secreted significant amounts of IL-1 beta (53.6 +/- 3.6 pg/mL), IL-6 (57.6 +/- 15.6 pg/mL), and GM-CSF (24 +/- 4 pg/mL) but not TNF-alpha. Exposure of human marrow megakaryocytes to IL-1 beta increased the levels of IL-6 (87.3 +/- 2.3 pg/mL) detected in the culture supernatants. Transforming growth factor- beta was also able to stimulate IL-6, IL-1 beta, and GM-CSF secretion, but was less potent than stimulation with phorbol-12-myristate-13- acetate (PMA). The secreted cytokines acted additively to maintain and increase the number of colony-forming unit-megakaryocytes colonies (approximately 35%). These studies demonstrate the production of multiple cytokines by isolated human bone marrow megakaryocytes constitutively or stimulated in vitro. The capacity of human megakaryocytes to synthesize several cytokines known to modulate hematopoietic cells supports the concept that there may be an autocrine mechanism operative in the regulation of megakaryocytopoiesis.

A combination of megakaryocyte growth and development factor and interleukin‐1 is sufficient to culture large numbers of megakaryocytic progenitors and megakaryocytes for transfusion purposes

“…The effects of IL-1 on platelet production could be partly indirect by its stimulating role in the formation of other cytokines. IL-1-induced production of IL-6 has been described both in humans (Brach et al, 1990;Jiang et al, 1994) and in mice (Kimura et al, 1990;Dan et al, 1995). In our culture system IL-6 production was observed if cells were cultured with PEGrHuMGDF and IL-1 (data not shown); this is in agreement with other papers in which IL-6 production by megakaryocytes was described (Jiang et al, 1994;Wickenhauser et al, 1995).…”

“…IL-1-induced production of IL-6 has been described both in humans (Brach et al, 1990;Jiang et al, 1994) and in mice (Kimura et al, 1990;Dan et al, 1995). In our culture system IL-6 production was observed if cells were cultured with PEGrHuMGDF and IL-1 (data not shown); this is in agreement with other papers in which IL-6 production by megakaryocytes was described (Jiang et al, 1994;Wickenhauser et al, 1995). However, in our culture system, presence of IL-6 in combination with PEG-rHuMGDF and IL-11 was not suf®cient to culture the high numbers of megakaryocytic cells obtained with IL-1.…”

The Efficacy of Recombinant Thrombopoietin in Murine and Nonhuman Primate Models for Radiation‐Induced Myelosuppression and Stem Cell Transplantation

“…The TPO effect on early hematopoietic progenitor cells of different lineages was unexpected but is in line with other observations [39,40] and consistent with the observation that its receptor is present on immature progenitor cells [7]. As megakaryocytes are capable of releasing various growth factors [41,42], the effect observed may be an indirect consequence of stimulation of the megakaryocyte lineage. Alternatively, TPO may synergize directly with growth factors such as kit ligand or flt-3 ligand to stimulate immature cells.…”

“…The mechanisms involved might therefore include activation of one or more cofactors required for the strong proliferative response observed. We also do not exclude the possibility that the effect of TPO on multilineage cells is augmented by the release of various cytokines by megakaryocytes [41,42] subsequent to stimulation by TPO, although the time frame observed makes such a mechanism unlikely.…”

Amicus or Adversary Revisited: Platelets in Acute Lung Injury and Acute Respiratory Distress Syndrome

“…A second unexplored possibility is that lung megakaryocytes have activities that contribute to pulmonary inflammation, injury, and repair independent of thrombopoiesis (13). Earlier experiments with megakaryocytes isolated from human bone marrow and CD34 1 hematopoietic progenitor cell-derived megakaryocytes demonstrated that these megakaryocytes synthesize cytokines and lipid mediators and respond to inflammatory stimulation (23,24), suggesting functions beyond platelet biogenesis. Transcript analysis of megakaryocytes isolated from murine lungs also supports this possibility (18).…”