A monoclonal antibody to platelet glycoproteins IIb and IIIa complex: its use in purifying human megakaryocytes from sternal bone marrow aspirates for immunofluorescence studies of Ia-like antigens.

A monoclonal antibody (PBM 6.4) to platelet and megakaryocyte glycoproteins IIb and IIIa has been obtained and used to purify human megakaryocytes from sternal bone marrow aspirates by a simple method, consisting of a Percoll gradient centrifugation followed by affinity adherence on PBM 6.4-coated plastic surface, "panning." Megakaryocytes, 80-90% pure and morphologically well preserved, were attached to poly-L-ornithine-coated multi-well microscope slides and immunofluorescence was done using monoclonal antibodies to human Ia-like antigens (DR, DC1). A higher proportion of DR-positive megakaryocytes was found, in comparison to the values reported by others, while DC1 antigen was detected on about 20% of megakaryocytes. The method described has the unique feature of enriching cells of the human megakaryocytic lineage from simple diagnostic sternal aspirates in an amount adequate for immunofluorescent and morphological analysis.