A FUCOSE-CONTAINING EPITOPE POTENTIALLY INVOLVED IN GAMETE INTERACTION ON THE HUMAN ZONA-PELLUCIDA

The oligosaccharide moiety of human, porcine and bovine zonae pellucid ae was studied with lectins and monoclonal antibodies specific for tri - or tetra-saccharidic epitopes containing at least one terminal alpha -L-fucose. Animal eggs were collected from follicular aspirates, human eggs were collected from in-vitro fertilization and embryo transfer p rogrammes and pooled into six groups. By direct immunofluorescence, th e lectins reactivity was detected for the animal or the human zonae po ols in the same way. Reactivity of Aleuria aurantia lectin demonstrate d the presence of alpha-L-fucose terminal residues in the zonae from t he three species studied. By indirect immunofluorescence, the 2-25 ant ibody reactivity was detected in every pool of human zonae whereas the re was no evidence of any antibody reactivity on animal zonae. Using a n anti-Lewis-b blood group antibody (2-25), we observed expression of this antigen as an intrinsic component of the human zona pellucida, in dependently of patients' Lewis red blood cell phenotypes. Antibody 2-2 5 inhibited the spermatozoa-zona binding in a hemizona assay, suggesti ng that this fucose-containing antigen could be part of a sperm - zona receptor.