Varying occurrence of gastroduodenal immunoreactive pancreatic secretory trypsin inhibitor.

Operative specimens from various parts of gastroduodenal mucosa were analysed for immunoreactive pancreatic secretory trypsin inhibitor (PSTI) using a peroxidase-antiperoxidase method. Normal gastric mucosa exhibited a varying degree of PSTI immunoreactivity, which was more pronounced in the foveolar cells of gastric mucosa of fundus type than in the non-pepsinogen producing antrum-pyloric mucosa. With the exception of metaplastic Paneth cells and some goblet cells, the intracellular content of PSTI was low in gastric mucosa with intestinal metaplasia. These findings may indicate that a PSTI immunoreactive substance has a role in the normal defence of the gastric mucosa.