Radioimmunoassay detection of endorphins from long-term culture of human pituitary tumour cells.

Using a sensitive and precise radioimmunoassay for human beta-endorphin, we have demonstrated the sustained secretion of opioid peptides from human pituitary tumour cells. Pituitary tumour tissue obtained from a patient with Nelson's syndrome was maintained in continuous monolayer culture and secreted both beta-lipotropin and beta-endorphin, with predominance of the latter. This is compatible with the idea that the beta-endorphin in normal human serum is secreted as such despite the predominance of beta-lipotropin compared with beta-endorphin in the anterior pituitary.