title: Binding of Leishmania promastigotes to macrophages.
abstract: Leishmania tropica promastigotes are easily attached to and engulfed by C3H peritoneal macrophages in vitro at 37 degrees C. Different sugars at 0.3-0.5 M inhibited in vitro the attachment of L. tropica promastigotes to C3H peritoneal macrophages with lactose (Gal-beta [1 leads to 4]Glc) being the most efficient. Inhibition of attachment is also affected by pre-treatment of promastigotes with galactose oxidase. Oligosaccharides extending from promastigote and amastigote cell surfaces contain an important proportion of non-reducing galactose as does the carbohydrate-rich factor (EF) excreted by promastigotes of L. tropica and L. donovani. This study suggests that Leishmania, an obligatory intracellular parasite, uses as a means of entering the host cell a cellular mechanism similar to that used in the removal of damaged cells from blood circulation. This mechanism is assumed to take advantage of the exposed sugars, particularly the exposed non-reducing galactose, on the parasite surface during the stage of attachment. Once the parasite is inside the cell, the EF it produces might have a protective function, being inhibitory to some of the host cell lysosomal enzymes.
mesh_terms: D000371:Agglutination; D000818:Animals; D001202:Ascitic Fluid / Q000166:cytology; D005690:Galactose / Q000032:analysis; D005692:Galactose Oxidase / Q000494:pharmacology; D007785:Lactose / Q000494:pharmacology; D037102:Lectins / Q000494:pharmacology; D007891:Leishmania / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D008264:Macrophages / Q000469:parasitology*; D051379:Mice; D008809:Mice, Inbred C3H; D010587:Phagocytosis / Q000187:drug effects
chemical_list: D037102:Lectins; D005692:Galactose Oxidase; D007785:Lactose; D005690:Galactose