Alpha-1-antitrypsin immunoreactivity in gastric carcinoid.

Alpha-1-antitrypsin (AAT) was demonstrated in tumour cells in three out of five cases of gastric carcinoma showing the histological characteristics of carcinoid tumour. It was also detected in normal stomach mucosa, but was not found in 10 cases of adenocarcinoma of intestinal or mucous cell type. The AAT-positive tumour cells were argyrophilic, PAS-positive and were negative for pancreatic and gastric hormones. These findings suggest a possible malignant proliferation of alpha-1-antitrypsin-containing cells in the stomach.