Increase of beta 1-6-branched oligosaccharides in human esophageal carcinomas invasive against surrounding tissue in vivo and in vitro. The -GlcNAc beta 1-6Man- (beta 1-6) branched N-glycosidic oligosaccharides expressed on tumor cells have been found to contribute to malignant and metastatic potential in experimental tumor models. Phaseolus vulgaris leukoagglutinin (L-PHA) requires the beta 1-6-linked lactosamine antenna for high-affinity binding and was used histochemically to characterize the distribution of these sugar structures in human esophageal squamous cell carcinomas from 42 patients. Leukoagglutinin-reactive carcinoma cells in the invasive tumors were distributed predominantly on the outer surface of the tumor adjacent to the surrounding tissue. Furthermore, when TE 1 cells, a human esophageal squamous cell carcinoma line, were cultured in a collagen gel matrix to obtain colonies in a three-dimensional form, these colonies exhibited high affinity for L-PHA binding only in the outer cell layer facing the collagen matrix, unrelated to the cell growth cycle. These findings suggest that the increase in beta 1-6-branched oligosaccharides in esophageal carcinomas is an important trait of the tumor in the invasion into the surrounding tissue. 