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.