Blood group activities in water-soluble glycoproteins and in microsomal fractions of gastric mucosa in peptic ulcer and gastric cancer patients.

The existence of ABH blood group activities in water-soluble glycoproteins of human gastric mucosa, particularly in peptic ulcer and gastric cancer patients was studied. Special attention was paid to the sampling technique which would allow one to get a more complete picture of the total gastric mucosal area. An attempt was also made to localize the blood group substances in subcellular fractions. The results seem to indicate that the secretion of A–H or B–H active substances is quite homogeneous. In the gastric cancer material occasional samples were lacking H-activity, and in special cases also B-activity. Two stomachs with peptic ulcer and four stomachs with cancer showed additional non-compatible A-activity, each in one sample. A genetically directed enzymatic basis for altered biosynthesis is suspected. The H-activity, present in addition to A- or B-activity in the supernatant of A or B persons, respectively, was totally lacking in the microsomal fractions, while considerable A- or B-activities were detectable. The possible importance of this observation concerning the pathway of the addition of oligosaccharide side chains to the growing polypeptide molecule is discussed. The possibility of an enzymatic modification of the glycoprotein molecules in a later step to explain the simultaneous occurrence of H-activity in secretion products is suspected. Additional non-compatible A-activity was also detected in the microsomal fractions derived from two cancerous stomachs and one with peptic ulcer.