The blood group activity of human gastric sulphoglycoproteins in patients with gastric cancer and normal controls.
Sulphoglycoproteins, isolated from human gastric juice, were observed to possess blood group activity, compatible with hosts' blood group in eighteen normal subjects and in nine patients with atrophic gastritis. The activities were of comparable magnitude with neutral glycoproteins of gastric juice as measured with haemagglutination inhibition test. The content of neutral glycoproteins is, however, about ten times that of sulphoglycoproteins and, it was thought, this would be the reason why the latter had been previously overlooked. 
 
In cases of gastric cancer, deviations were observed in compatibility with hosts' blood group. Sulphoglycoproteins derived from cancerous gastric juice of all five patients belonging to blood group B, showed A-activity, often with high titre in addition to B- and H-activity. In seven cases belonging to blood group O, four showed A-activity in addition to H-activity, and two cases showed A- and B-activity in their gastric sulphoglycoproteins. Of eleven cancer cases belonging to blood group A, ten showed only compatible A- (and H-) activity, and in one case weak B-activity in the gastric sulphoglycoproteins. The observed differences were thought to be mainly in sulphoglycoproteins of gastric juice.