Interleukin-6 and its receptor are expressed by human megakaryocytes: in vitro effects on proliferation and endoreplication

Blood. 1991 Feb 1;77(3):461-71.

Abstract

Interleukin-6 (IL-6) is a pleiotropic cytokine that plays an important role in the megakaryocytic differentiation. Recently, we have observed that IL-6 is synthesized by several human cell lines with megakaryocytic features. In this study, we have investigated whether a similar phenomenon occurs during normal megakaryocytic differentiation. Human megakaryocytes (MK) were obtained by culturing normal marrow in liquid culture with aplastic plasma (AP). First, an IL-6 secretion in bone marrow culture enriched in MK as well as in purified MK populations was demonstrated by a biologic assay. Second, IL-6 mRNA was detected in a purified population of MK by the polymerase chain reaction and dot blot analysis. IL-6 mRNA and protein were undetectable in platelets. Third, in situ hybridization procedure demonstrated the presence of IL-6 mRNA in individual immature MK. Fourth, IL-6 protein was detected in MK at the unicellular level by an immunoalkaline phosphatase technique using a monoclonal antibody against IL-6. Furthermore, the presence of IL-6 receptor (IL-6-R) on MK was demonstrated by in situ hybridization using an IL-6-R probe and in situ autoradiography after binding with [125I]-labeled recombinant IL-6. The IL-6 endogenously produced in liquid cultures containing normal human plasma or AP was subsequently neutralized. This resulted in a 50% decrease of the MK growth with a minor shift in the ploidy distribution toward lower values. In semisolid cultures the addition of anti-IL-6 antibodies led to a 42% decrease in colony number in cultures stimulated by IL-3 but not in other conditions of culture. These results suggest that normal human megakaryocytopoiesis might be regulated in part by an IL-6 autocrine loop.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal
  • Autoradiography
  • Bone Marrow Cells
  • Cell Differentiation / drug effects
  • Cell Differentiation / physiology
  • Cell Division / drug effects
  • Cell Division / physiology
  • Cell Line
  • Cell Transformation, Neoplastic / drug effects
  • Cell Transformation, Neoplastic / genetics
  • Cell Transformation, Neoplastic / pathology
  • Gene Expression
  • Humans
  • Immunoblotting
  • Interleukin-6 / genetics
  • Interleukin-6 / physiology*
  • Megakaryocytes / pathology
  • Megakaryocytes / ultrastructure*
  • Nucleic Acid Hybridization
  • Ploidies
  • Polymerase Chain Reaction
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptors, Immunologic / genetics
  • Receptors, Immunologic / physiology*
  • Receptors, Interleukin-6
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / physiology

Substances

  • Antibodies, Monoclonal
  • Interleukin-6
  • RNA, Messenger
  • Receptors, Immunologic
  • Receptors, Interleukin-6
  • Recombinant Proteins