Characterization of a series of novel fucose-containing glycosphingolipid immunogens from eggs of Schistosoma mansoni.

Lipid extracts of eggs, worms, and cercariae of the parasitic trematode Schistosoma mansoni have been shown to contain a large number of highly immunogenic glycolipids (Weiss, J. B., Magnani, J. L., and Strand, M. (1986) J. Immunol. 136, 4275-4282). Three fractions of schistosome egg glycolipids were selected on the basis of their reactivity with an anti-schistosome monoclonal antibody (128C3/3), which recognizes a developmentally regulated carbohydrate epitope present on both glycolipid and glycoprotein antigens from S. mansoni. These fractions were purified by silica gel chromatography and preparative high performance thin layer chromatography and characterized by monosaccharide, fatty acid, and linkage analysis with gas chromatography-mass spectrometry, as well as by positive and negative ion fast atom bombardment-mass spectrometry. The immunogens were shown to be glycosphingolipids having homologous structures based on a highly novel extension of glucosylceramide. Monosaccharide inhibition studies indicated that the epitope recognized by 128C3/3 residues in an outer region of the immunogens consisting of Fuc2GlcNAc (where Fuc is fucose) repeating units. The largest antigen characterized may have the following structure, based on the evidence presented in this paper. [sequence: see text] The evidence indicated the existence of a series of glycan structures created by deletions of one or more Fuc1----3 side chains from the above structure.