Lectin-binding Patterns of the Normal Human Esophageal Epithelium as Revealed by Light and Electron Microscopy

Abstract

Lectin binding sites in the normal human esophageal epithelium were studied by light and electron microscopy using lectins as a probe. Lectins used were concanavalin A (ConA), wheat germ agglutinin (WGA), Ricinus communis agglutinin (RCA), Dolichos biflorus agglutinin (DBA), peanut agglutinin (PNA), soybean agglutinin (SBA), and Ulex europeus agglutinin-1 (UEA-1). For light microscopy, specimens were obtained by autopsy from 37 patients without esophageal disease and malignancy in the upper gastrointestinal tract. The ABC method with biotinyl lectins was employed. ConA diffusely stained all the layers of the esophageal epithelium. WGA and RCA stained the plasma membrane of the cells in all the layers. In some cases, the middle and the superficial layers were intensely stained with WGA, whereas the basal layer was intensely positive for RCA reaction. PNA, SBA and UEA-1 preferentially stained the middle layer. No positive staining for DBA was seen. The specificity of each lectin reaction was confirmed with appropriate cytochemical control experiments. For electron microscopy, specimens obtained by endoscopic biopsy were fixed, frozen-sectioned and incubated with HRP-labeled lectins. Positive reaction for these lectins was found in the plasma membrane, especially along the desmosomes, and also in the Golgi membranes of the epithelial cells. In addition, ConA staining was seen in the nuclear envelope and endoplasmic reticulum also. These results suggest that cell surface sugar residues change during the course of the cellular differentiation from the basal to the superficial layer of the human esophageal epithelium.