Antisera raised against eledoisin and kassinin detect elevated levels of immunoreactive material in plasma and tumor tissues from patients with carcinoid tumors.

Radioimmunoassays based on antisera raised against the tachykinins eledoisin (antiserum E7) and kassinin (antiserum K12) were used to measure the concentration of tachykinin-like immunoreactivity (TKLI) in plasma from 52 healthy subjects. 65 patients with carcinoid tumors (of which 46 had symptoms of both flushing and diarrhoea), and 6 patients with endocrine pancreatic tumors. The antisera did not crossreact with substance P (SP). Elevated concentrations of TKLI, as compared with healthy subjects, were found in 75% of the carcinoid patients, but in none of the patients with pancreatic tumors. Tumor metastases from 8 of the carcinoid patients all contained TKLI. Ion-exchange chromatography of plasma samples and tumor tissue extracts indicated the presence of several immunoreactive molecular forms. The elution patterns of the immunoreactivity detected by antisera E7 and K12 were similar, indicating that the same molecular species are measured by these antisera. None of the components coeluted with synthetic SP. One of the immunoreactive components in carcinoid tumor extracts coeluted with synthetic NKA. The major immunoreactive components in plasma from the patients eluted in a position different from that of all currently known mammalian tachykinins. Tachykinin immunoreactive material detected in tumor tissue and plasma of patients with carcinoid tumor may play a role in the symptomatology of the carcinoid syndrome.