Interferon-alpha-2b alone and combined with octreotide in primary carcinoid cell-cultures.

Interferon and octreotide are two main therapeutic options in metastatic carcinoid disease. In primary cell cultures prepared from 26 previously untreated carcinoid patients interferon-alpha 2b (alpha-INF), alone and combined with octreotide, significantly reduced medium serotonin (5-HT). The amines were measured with reversed phase HPLC and electrochemical detection, total DNA with a photometric method. Interferon lowered the medium concentration of serotonin to 53% (range 42-79%), octreotide alone to 44% (range 23-48%). Neither interferon, octreotide nor the combined treatment decreased DNA content. Octreotide had no effect on intracellular 5-HT. Both interferon alone and combined with octreotide lowered intracellular 5-HT concentrations significantly. This may represent a direct biochemical effect of interferon on tryptophan metabolism.