1. ^*Clinical Research Centre, Watford Road, Harrow, Middlesex HA1 3UJ, UK
2. ^†Wistar Institute of Anatomy, Philadelphia, Pennsylvania 19104, USA
3. ^‡Department of Genetics, University of Cambridge, Cambridge CBQ 3EH, UK

Abstract

There is much interest in developmentally regulated molecules which may have function in cell interactions and sorting during embryogenesis and differentiation. Numerous antisera have been raised which detect antigens that are expressed in early embryonic cells and become restricted during differentiation, being expressed in only a minority of adult cells (reviewed in refs 1–3). The precise antigenic determinants recognized by such antisera have not been defined. However, studies using a hybri-doma antibody against mouse spleen cells⁴ and monoclonal autoantibodies of patients with cold agglutinin disease⁵ have shown that two defined carbohydrate antigen systems, the Forssman and the li antigens, have stage-specific expression in early mouse embryos. We now describe evidence that the stage-specific embryonic antigen SSEA-1 (ref. 6) involves the carbohydrate sequence Gal1 4GlcNAc ^1,3 Fuc This determinant is formed by 1 3 fucosylation of blood group I or i antigens which are branched or linear oligosaccharides, respectively^7–9, built of Gal1 4GlcNAc units and known as type 2 precursor chains¹⁰ of the major blood group antigens. Thus, we introduce the concept of simple glycosylation changes as a basis for stage-specific expression of embryonic antigens.