Expression of type 1 blood group precursor in human gastric carcinoma.

The surface epithelium of normal gastric mucosa from patients with gastric adenocarcinoma expressed the type 1 blood group precursor only in Lewis (Le) non-secretor individuals, Le a+b- (se/se, Le/-) and Le a-b- (se/se, le/le). In secretors, the superficial mucosa was negative. Deep areas of the mucosa showed no type 1 precursor regardless of secretor status. Expression of type 1 precursor was anomalously found in neoplastic cells in 14 of 16 Le a-b+ (secretors) patients and in 4 of 5 Le a-b- (secretors) patients. The 1 Le a-b- non-secretor carcinoma expressed type 1 precursor strongly. 6 of 8 Le a+b- non-secretor carcinomas showed positivity for the monoclonal antibody K-21. Thus the type 1 precursor reacted with the non-neoplastic gastric surface of non-secretors but not with those of secretors, and also with most gastric adenocarcinoma regardless of secretor status and Lewis phenotype.