Human junctional epithelium: demonstration of a new marker, its growth in vitro and characterization by lectin reactivity and keratin expression.

We have studied lectin reactivity in normal human junctional, sulcular, and attached gingival epithelia with 15 lectins and identified the epithelia by parallel staining with monoclonal anti-keratin antibodies. Dolichos biflorus agglutinin reacted uniquely with junctional epithelium, not staining other gingival cells of non-blood group A1 donors. We have demonstrated that the moiety recognized in junctional epithelium is not blood group A1 antigen or Tn antigen. Using a panning technique with this lectin to isolate the cells, we have grown keratinocytes from human junctional epithelium, and compared their phenotype in vitro to that of cells grown from the sulcular and attached gingival epithelium. Colonies established from each epithelial type were examined in frozen section with the anti-keratin antibodies. All expressed keratin 14 (keratinocyte marker), keratins 4 and 13 (suprabasal non-cornification markers), and keratins 7, 18, and 19 (simple epithelia keratins). Keratins 1, 10, and 8 were not expressed. Vimentin, the intermediate filament of mesenchymal cells, was also expressed by all types of cells in culture. Thus we have shown that when cells from the three areas of the gingiva were grown in culture they revert to one phenotype, at least with respect to their keratin expression. These results support the hypothesis that the epithelial phenotype is influenced by the sub-epithelial mesenchyme, and it is this that is responsible for the unique phenotype of the junctional epithelium.