Carcinoid granule extract contains antigenic determinants common to peptide hormone-producing cells and endocrine tumours.

Some soluble proteins, such as the chromogranins, are found in nearly all peptide hormone-producing cells. Little is known about their functional role, although they may act as enzymes or represent structural proteins. In the present study we have isolated granules from an ileal carcinoid tumour and raised antibodies to protein constituents within them. The antiserum proved to be useful for the immunohistochemical demonstration of peptide hormone-producing endocrine tumours in general and for the demonstration of most peptide hormone-producing cells.