Isolation of human megakaryocytes by immunomagnetic beads

Summary. A simple method was developed to purify human megakaryocytes to homogeneity from normal bone marrow aspirates. An initial separation of marrow between 1.020 and 1.050 g/ml. Percoll® density cut was used to enrich megakaryocytes. After washing, the cells were suspended with immunomagnetic beads which were coated with sheep anti‐mouse IgG antibody and treated with anti‐human glycoprotein (GP) IIb/IIIa monoclonal antibody, or the cells were treated with human platelet GP IIb/IIIa monoclonal antibody and suspended with the immunomagnetic beads which were coated with sheep anti‐mouse IgG antibody. Megakaryocytes were selectively separated using a magnet. All of the isolated cells were morphologically recognizable megakaryocytes. 1.5–3.1 × 104 megakaryocytes were obtained from 1.7–4.5 × 108 bone marrow nuleated cells. These cells were all positive in immunoenzymatic staining for GP IIb/IIIa. Megakaryocytes obtained by this method responded to recombinant human GM‐CSF (rhGM‐CSF) showing an increased 3H‐thymidine (3H‐dT) incorporation. These data show that this method is useful for obtaining pure megakaryocyte populations which can be submitted to comprehensive biological studies.