Isolation of a sulfated glycopeptidic antigen from human gastric tumors: its localization in normal and cancerous gastrointestinal tissues.

A sulfated glycopeptidic antigen (SGA) was purified from papain-digested cancerous human gastric mucosa. The amino acid composition of this antigen was characterized by a high percentage of threonine and proline. Serine was present in small quantities and aromatic amino acids were absent. The amount of sulfate present was evaluated at 7.5%. Fucose, galactose, N-acetyl glucosamine, N-acetyl galactosamine and sialic acid were found to be present in the molar ratio 1:4.6:3.0:6.2:5.0. With immunofluorescence techniques, a rabbit antiserum against the sulfated glycopeptide stained adult gastric mucosa when this tissue had intestinal metaplasia and stained the goblet cells of the intestinal tract (small and large intestines). About 50% of colonic carcinomas and some gastric carcinomas contained SGA. This sulfated antigen was present in well-differentiated tumors and there was a good correlation between tumoral acid mucous secretory activity and the SGA positivity.