The liver flukes Fasciola gigantica and Fasciola hepatica express the leucocyte cluster of differentiation marker CD77 (globotriaosylceramide) in their tegument

Glycosphingolipids from the parasitic liver flukes Fasciola gigantica and F asciola hepatica were isolated and their carbohydrate moieties were structu rally analysed by methylation analysis, exoglycosidase treatment, on-target exoglycosidase cleavage and matrix-assisted laser desorption/ionisation ti me-of-flight mass spectrometry. For both liver fluke species, the ceramide monohexosides Gal1-ceramide and Glc1-ceramide were found in relative amount s of 1.0 to 0.1, respectively. From F: gigantica, the ceramide dihexoside w as isolated in sufficient amounts to be structurally determined as lactosyl ceramide, Gal beta4-Glc1-ceramide, while for both liver fluke species the c eramide trihexoside was shown to be Gal alpha 4Gal beta4- Glc1-ceramide, wh ich is designated as either globotriaosylceramide, pk-blood group antigen o r CD77 leucocyte cluster of differentiation antigen. To our knowledge, this is the first report on the expression of globe-series glycosphingolipids i n non-mammalian species. Ceramide analysis of ceramide monohexosides yielde d as major components octadecanoic and 2-hydroxyoctadecanoic fatty acids to gether with C18- and C20-phytosphingosines. By the use of an anti-CD77 mono clonal antibody and the Escherichia coli Shiga toxin B1 subunit, globotriao sylceramide could be immunolocalised to the tegument of F: hepatica cryosec tions. The sharing of CD77 between liver flukes and their mammalian hosts f its in with the concept of molecular mimicry, which is closely parallel to the established imitation of host CD15 (Lewis X) displayed by the blood flu ke Schistosoma mansoni.