Lectin--peroxidase conjugates in histopathology of gastrointestinal mucosa

Peroxidase (HRP) conjugates of Dolichos biflorus agglutinin (DBA), Arachis hypogaea agglutinin (PNA) and Ulex europaeus agglutinin I (UEA I) were used as specific molecular probes in order to describe histological patterns of carbohydrate moieties in glycoconjugates of gastric mucosa. Specimens of normal mucosa, metaplasias and carcinomas were fixed, embedded in paraffin and stained with lectins by a postembedding technique. In normal mucosa, DBA reacted with surface epithelial, parietal and antral gland cells; neck cells did not react. In single goblet cell metaplasia, with few exceptions, goblet cells showed DBA binding. In contrast, mainly negative goblet cells were seen in intestinal metaplasia. In gastric carcinomas of intestinal or diffuse types, heterogeneous staining patterns were observed. Large numbers of mucus-producing surface epithelial, neck and antral gland cells stained with PNA-HRP conjugates. Parietal cells did not react. Among the chief cells only few showed PNA binding. In single goblet cell metaplasia, equal numbers of goblet cells were positive or negative, whereas goblet cells in intestinal metaplasia were mainly unstained. Carcinomas contained both PNA-positive and PNA-negative cells; PNA-positive cells occurred preferentially in the tumor periphery. UEA I - HRP conjugates stained the bulk of surface epithelial and neck cells; chief cells and antral gland cells were mainly positive, too. Parietal cells did not react. In single goblet cell metaplasia and intestinal metaplasia, UEA I-positive as well as UEA-negative goblet cells occurred. Striated cells exhibited a great variety of lectin reactivity. Carcinomas also showed a heterogeneous staining pattern. Under both normal conditions and in carcinoma development, qualitative and quantitative differences in the composition of glycoconjugates must be expected.