In-vitro secretion of ACTH in Nelson's syndrome.

Cell suspensions of ACTH cell adenomas of 10 patients with Nelson's syndrome were investigated for in-vitro secretion of ACTH. Two incubation systems, one using incubation beakers and the other a superfusion system, were employed. The cells were tested for their reactivity to lysine-vasopressin (LVP), cortisol, and combinations of both. LVP regularly provoked a rapid significant increase of ACTH secretion. The effect of cortisol was heterogeneous. Paradoxical initial stimulatory effects of cortisol were observed. There was a suppressive effect in some patients, which correlates to low proliferative activity in histological evaluation. In both systems a low secretory activity coincided with high proliferative activity in vivo.