Pancreastatin-like immunoreactivity has been demonstrated in human
carcinoid tumors by immunohistochemistry and radioimmunoassay, employing
antisera raised to a synthetic C-terminal fragment of porcine
pancreastatin. Immunohistochemistry revealed intense immunoreactivity in all
tumors. By radioimmunoassay, high concentrations of
pancreastatin-like immunoreactivity were measured in
carcinoid tumors arising from the fore-gut (mean +/- S.D. and range: 369 +/- 955 and 9.4-3670 pmol g-1, respectively, n = 14), mid-gut (mean +/- S.D. and range: 1354 +/- 1538 and 337-3978 pmol g-1, respectively, n = 5) and in
metastases associated with mid-gut
tumors (mean +/- S.D. and range: 684 +/- 739 and 31-2255 pmol g-1, respectively, n = 7), compared to corresponding normal tissues (less than 1.4 pmol g-1). Individuals with hepatic
metastases and
carcinoid syndrome had elevated circulating levels of
pancreastatin-like immunoreactivity (mean +/- S.D. and range: 770 +/- 1249 and 42-4120 pmol l-1; n = 12), significantly above the normal, fasting range (mean +/- S.D. and range: 14.9 +/- 7.5 and 4-37.5 pmol l-1, respectively, n = 42). However, patients with non-metastatic
carcinoid tumors (n = 4), who had been clinically cured after primary
tumor resection, had plasma levels within the normal range. Chromatographic analysis of extracts of primary lung and ileal
tumors, hepatic
metastases from ileal
tumors and plasma from individuals with
carcinoid syndrome revealed molecular heterogeneity of
pancreastatin-like immunoreactivity.