Changes in the expression and polarization of blood group I and i antigens in post-implantation embryos and teratocarcinomas of mouse associated with cell differentiation

Abstract

The human monoclonal antibodies anti-I Ma and anti-I Step reactive with the branched structure: ▪ and the anti-i antibody Den reactive with the linear oligosaccharide sequence: Galβ1 → 4GlcNAβ1 → 3Galβ1 → 4GlcNAc-have been used as reagents in indirect immunofluorescence studies of 5–7-day mouse embryos and of mouse teratocarcinoma cells undergoing differentiation in culture. Immunofluorescence staining of disaggregated cells in suspension and of cryostat sections of intact embryos and embryoid bodies have revealed marked changes in the expression and polarization of these antigens associated with differentiation. Undifferentiated embryonal carcinoma cells were rich in surface-associated and cytoplasmic I antigen. Both in the embryos and in teratocarcinoma systems, differentiation into primary endoderm was associated with the appearance of i antigen in the cytoplasm and the surface of the cells. In endoderm cells examined in situ both Ii antigens were asymmetrically distributed in the ‘luminal’ aspects of the cells and abundantly expressed in cytoplasmic projections into the blastocoelic cavity. In embryoid bodies after 7 weeks of culture, differentiation into other types of epithelia was associated with intense I staining on the apical rather than the basolateral surface in one cell type, and a lack of Ii staining in two other cell types.