Production and secretion of pancreatic secretory trypsin inhibitor in normal human small intestine.

The aim of this study was to prove the production and secretion of pancreatic secretory trypsin inhibitor (PSTI) in human small intestine. To achieve this we analyzed the content of immunoreactive PSTI (irPSTI) in rinsing fluid from isolated small intestine, using the urea method to estimate the volume of epithelial lining fluid recovered. IrPSTI, measured by an enzyme-linked, immunosorbent assay (ELISA), was present in both free and complexed form. The free PSTI showed intact biologic activity, binding trypsin in stable complexes. The complexed PSTI was dissociated on acidification. With the reverse transcriptase polymerase chain reaction (RT-PCR) and Southern blot hybridization, PSTI mRNA was demonstrated in the mucosa of the ileum. These findings indicate that PSTI is produced and secreted in the small intestinal epithelium and may be part of defence system in intestinal mucosa.

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.

Quantification of pancreatic secretory trypsin inhibitor in colonic carcinoma and normal adjacent colonic mucosa.

AIMS: To measure the content of immunoreactive human pancreatic secretory trypsin inhibitor (irPSTI) in colonic carcinoma and adjacent normal colonic mucosa. METHODS: From a stable hybridoma cell line producing monoclonal antibodies specific for human PSTI, a specific enzyme linked immunosorbent assay (ELISA) for human PSTI was developed. In a precipitation assay system these antibodies bound human PSTI in a dose-dependent manner. The specimens were obtained from resectional surgery. RESULTS: The content of irPSTI was 19.9 micrograms/g protein (0.55 micrograms/g tissue wet weight) in colonic carcinoma. In adjacent normal colonic mucosa 43.6 micrograms/g protein (1.12 micrograms/g tissue wet weight) was shown. CONCLUSIONS: The enzymatic degradation of surrounding tissue necessary for tumour cell invasion could be facilitated by this relative deficit of the inhibitor in infiltrative carcinoma.

Immunoreactive pancreatic secretory trypsin inhibitor in normal, inflammatory and neoplastic gallbladders.

Operative specimens from normal, inflammatory and neoplastic gallbladders were analyzed for immunoreactive pancreatic secretory trypsin inhibitor (irPSTI) using a peroxidase-antiperoxidase method. In normal and inflammatory gallbladders no irPSTI was demonstrated, while irPSTI was found in neoplastic gallbladders.

Immunohistochemical demonstration of pancreatic secretory trypsin inhibitor in normal and neoplastic colonic mucosa.

Specimens of normal and neoplastic colonic mucosa from 52 patients were analysed by immunohistochemistry using a monospecific polyclonal antiserum against human pancreatic secretory trypsin inhibitor (PSTI). In normal colonic mucosa PSTI was found in the goblet cells in the basal parts of the crypts. In adenomas of tubular, villous, and tubulo-villous types PSTI was also found in the upper parts of the polyps, usually occurring in the regeneration zone. There was a more intense staining reaction in polyps with increased atypia. Carcinomas of different types and of various grades of differentiation and of in situ type did not contain PSTI. These findings indicate that PSTI could be a marker for adenomatous rather than carcinomatous epithelium in the colon. Furthermore, the absence of the inhibitor in malignant cells might facilitate tissue invasion by malignant cells because of deficient protease inhibition.