Pulmonary carcinoids. Immunohistochemical demonstration of brain-gut peptides.

Antisera raised against serotonin, gastrin, somatostastin, motilin, bombesin, calcitonin, secretin, glucagon, ACTH, neurotensin, and pancreatic polypeptide carboxyterminal hexapeptide were employed to immunohistochemically stain seven pulmonary carcinoids. Argentaffin and argyrophil stains were also performed on all cases. Serotonin-like immunoreactivity was present in four tumors, pancreatic polypeptide-like immunoreactivity in four tumors, bombesin-like immunoreactivity in two tumors and ACTH-like immunoreactivity in one tumor. The cells shown to contain neuroendocrine products constituted a minority cell population in all tumors except the ACTH-immunoreactive tumor. This study suggests that pulmonary carcinoids, like their abdominal counterparts, contain a variety of neuroendocrine products, and may produce more than one neuroendocrine product. Serotonin and pancreatic polypeptide-like immunoreactivity were the most prevalent neuroendocrine products demonstrable in this study.