RECEPTORS FOR CARBOHYDRATE LIGANDS INCLUDING HEPARIN ON THE CELL-SURFACE OF LEISHMANIA AND OTHER TRYPANOSOMATIDS

By employing neoglycoproteins (NGP) and glycosaminoglycans, the detect ion of endogenous glycoligand-binding sites has become possible. Monit oring specific binding of 11 of these sugar receptor-specific tools, 1 3 trypanosomatids of monogenetic genera Blastocrithidia, Crithidia, He rpetomonas, and Leptomonas and digenetic genera Endotrypanum, Leishman ia, and Sauroleishmania were analysed by agglutination and fluorescenc e assays. NGP showed agglutination reactions only with the digenetic b ur not with the monogenetic species. Sensitive flow cytofluorimetric i nvestigations revealed that the apparently different reactivity to NGP is due to a pronounced quantitative difference in expression of bindi ng sites between mono-and digenetic flagellates. Moreover, flow cytofl uorimetry was used to demonstrate the occurrence of receptor sites for heparin on the cell surfaces of all trypanosomatids. An indication fo r a correlation of the binding capacity for the NGP N-acetyl-beta-D-gl ucosamine and heparin to differences in the pathogenicity of parasites was observed for Leishmania donovani as well as Leishmania enriettii. Infective populations of these species contained a significantly high er number of cells which had bound N-acetyl-beta-D-glucosamine and hep arin than noninfective (long-term in vitro-cultured) populations. The results of the present report additionally support the hypothesis that lectin-carbohydrate interactions with neutral sugar moieties and hepa rin or heparin-like molecules participate in the interactions between trypanosomatids and host (cells), and that the detected binding sires for carbohydrates and heparin may thus be referred to as potential vir ulence factors.