[Specificity control in the immunohistochemistry of enteral peptide hormones]

A great variety of peptide hormones have been demonstrated by immunocytochemical means in endocrine cells of the digestive system. Usually the specificity immunostaining in these cells is checked by antigen-adsorption of the antisera. This kind of specificity control, however, examines only antibody non-specificity but not staining non-specificity. Indeed staining non-specificities caused by ionic binding mechanisms are of considerable significance, at least for the immunostaining of some endocrine cell types (e.g. pancreatic glucagon- and PP-cells, pyloric gastrin-cells, intestinal GLI-cells). Therefore immunoreactivities of these cell types should be investigated under various experimental conditions. According to our present findings the following investigations should be performed to exclude staining non-specificities in immunostained endocrine cells of the digestive system: 1. Running of ascending dilutions of primary and secondary antisera. 2. Comparative investigations using crude antisera and purified antibodies against the peptide in question. 3. Use of phosphate buffered saline (PBS) with a relatively high salt content as a dilution agent for the antisera.