Tissue specimens from 5 patients with metastatic midgut
carcinoid tumours were kept in organ culture for up to 6 months. The tumour cells were confined to the
suspension in the form of condensed cell clusters and appeared to retain their endocrine characteristics. Radioimmunoassay for
tachykinin immunoreactivity showed high concentrations in 4 out of 5
culture media. The concentrations were highest in the beginning of the experiment, but subsequently decreased. The 4 patients from which these tumours were taken had all elevated
tachykinin concentrations in extracted plasma. The fifth culture medium had low
tachykinin concentration, and the concentration in extracted plasma from this patient was within the normal range. Reversed-phase high-performance liquid chromatography of the
culture media with elevated
tachykinin concentrations revealed immunoreactive components with the characteristics of synthetic
neuropeptide K,
neurokinin A and
eledoisin, components also found in plasma and tumour tissues of
carcinoid patients. Our findings indicate that
carcinoid tumour cells produce
tachykinins. These
peptides are biologically very active, resulting in flush and
hypotension when infused intravenously into normals, and might contribute to the clinical symptoms of the
carcinoid syndrome.