Lectin receptors on human blood and bone marrow cells and their use in cell separation

A series of fluorescein-conjugated lectins (Sophora japonica agglutinin, Helix pomatia agglutinin, peanut agglutinin, the erythroagglutinin from Phaseolus vulgaris, pokeweed mitogen, wheat germ agglutinin and the fucose-binding lectin from Lotus tetragonolobus) were analyzed for their binding to human peripheral blood cells with a fluorescence-activated cell sorter. Most of the lectins showed increasing cell binding in the order erythrocytes less than lymphocytes less than monocytes less than neutrophils and the degree of fluorescence was not related to the major blood groups. The fucose-binding lectin (FBP) was the main exception in that it appeared to bind only to blood neutrophils. From an analysis of the binding of this lectin to human bone marrow cells it was found that the degree of binding within the granulocytic series increased with progressive differentiation. Marrow monocytes and nucleated erythroid cells bound to FBP in contrast to monocytes and non-nucleated red cells in the peripheral blood which showed negligible binding. Lymphocytes both in the marrow and blood displayed negligible binding of FBP. These properties allowed an enrichment of haemopoietic progenitor (colony-forming) cells from human marrow cell suspensions and a depletion of colony-inhibiting cells, when these were present, by selection of cells with the appropriate fluorescence intensity.