Expression of Lex antigen in Schistosoma japonicum and S.haematobium and immune responses to Lex in infected animals: lack of Lex expression in other trematodes and nematodes

Adults of the human parasitic trematode Schistosoma mansoni, which causeshepatosplenic/intestinal complications in humans, synthesizeglycoconjugates containing the Lewis x (Lex) Galbeta1-->4(Fucalpha1-->3)GlcNAcbeta1-->R, but not sialyl Lewis x (sLex), antigen. We nowreport on our analyses of Lexand sLexexpression in S.haematobium andS.japonicum, which are two other major species of human schistosomes thatcause disease, and the possible autoimmunity to these antigens in infectedindividuals. Antigen expression was evaluated by both ELISA and Westernblot analyses of detergent extracts of parasites using monoclonalantibodies. Several high molecular weight glycoproteins in both S.haematobium and S. japonicum contain the Lexantigen, but no sialylLexantigen was detected. In addition, sera from humans and rodents infectedwith S.haematobium and S.japonicum contain antibodies reactive with Lex.These results led us to investigate whether Lexantigens are expressed inother helminths, including the parasitic trematode Fasciola hepatica , theparasitic nematode Dirofilaria immitis (dog heartworm), the ruminantnematode Haemonchus contortus , and the free-living nematode Caenorhabditiselegans . Neither Lexnor sialyl-Lexis detectable in these other helminths.Furthermore, none of the helminths, including schistosomes, express Lea,Leb, Ley, or the H- type 1 antigen. However, several glycoproteins from allhelminths analyzed are bound by Lotus tetragonolobus agglutinin , whichbinds Fucalpha1-->3GlcNAc, and Wisteria floribunda agglutinin, whichbinds GalNAcbeta1-->4GlcNAc (lacdiNAc or LDN). Thus, schistosomes may beunique among helminths in expressing the Lexantigen, whereas many differenthelminths may express alpha1,3-fucosylated glycans and the LDN motif.