Use of lectins for characterization and purification of human bone marrow cells that express CD34

The binding of lectins to nucleated cells from human bone marrow was studied in a search for markers that can be used to subdivide further immature hemopoietic cells that are characterized by their expression of CD34. Low-density bone marrow cells were indirectly labeled with biotinylated lectins and streptavidin-R-phycoerythrin (SA-RPE) together with FITC-labeled monoclonal anti-CD34. Four-parameter flow cytometric analysis was then performed and list mode data analyzed. Of the 21 lectins tested, only a few showed differential staining of CD34+ versus CD34- cells. These include soybean agglutinin (SBA) and Ulex europaeus agglutinin I (UE). Lycopersicon esculentum (LE) and Erythrina cristigalli (EC) reacted preferentially with, respectively, CD34+ and CD34- cells, suggesting their usefulness in some method to enrich for CD34+ cells. This possibility was tested by passing cells labeled with biotinylated lectins over a column containing streptavidin-coated beads. CD34+ cells could be enriched > 10-fold by competitive (sugar) elution of LE-labeled cells from the column. Similarly, depletion of biotinylated EC-labeled cells by passage through the streptavidin column enriched CD34+ cells several fold. The results of these studies document the reactivity of a large panel of lectins with subpopulations of nucleated bone marrow cells and indicate that certain lectins could possibly be used for development of cell separation procedures aimed at the selective enrichment of cells that express CD34.