Detection of membrane lectins on the surface of hemopoietic progenitor cells and their changing pattern during...

To probe for the presence of membrane lectins on hemopoietic progenitors capable of reacting with specific sugars, we synthesized a group of neoglycoprotein reagents by covalently binding biologically relevant monosaccharides to bovine serum albumin (BSA). These reagents were incubated with marrow cells that were subsequently agglutinated on a layer of BSA. The concentrations of various progenitor cells were determined in agglutinated and nonagglutinated fractions using standard clonal assays. Spleen colony-forming units, mixed lineage colony-forming units, and colony-forming units in culture were preferentially agglutinated by galactosyl- and mannosyl-BSA, but not by fucosyl-BSA, indicating the presence of membrane lectins on the surface of these cells with galactosyl and mannosyl specificities. Differentiation in the erythroid direction was associated first with the loss of galactosyl-recognizing system so that erythroid burst-forming units demonstrated only mannosyl-recognizing system. Further differentiation into erythroid colony-forming units was associated with the loss of mannosyl-reacting system as well but the development of a new fucosyl-reacting system. In every case, the agglutination was reversible and preventable in the presence of competing sugars, indicating the specificity of the reaction. Further characterization of these membrane lectins may shed light on their function in cellular interactions in hemopoiesis.