Pancreatic secretory trypsin inhibitor in human Brunner's glands

Brunner's glands (duodenal glands) in humans are located mainly in the two proximal thirds of the duodenum. They are known to produce and secrete mucin. In recent years, human Brunner's glands have also been shown to express immunoreactivity toward epidermal growth factor-urogastrone (EGF-uro) and lysozyme. These proteins are considered to have a protective function within the gastrointestinal canal. Human pancreatic secretory trypsin inhibitor (PSTI) was recently identified in Brunner's glands. This present study was done by an immunohistochemical method, using monospecific polyclonal antibodies against human PSTI and human lysozyme, respectively. McManus/Alcian blue mucin staining was used to clarify the distribution of mucin. We found immunoreactive PSTI (irPSTI) in seven out of ten specimens. Lysozyme and mucin were present in all ten. While virtually all cells were stained for lysozyme and mucin, irPSTI was restricted to separate lobules and to cells in the ducts.