IMMUNOREACTIVE β-MSH IN HUMAN PLASMA AND IN A CORTICOTROPHIC ADENOMA CULTURE MEDIUM. ITS RELATION TO THE LIPOTROPHINS

Abstract

To characterize more accurately the relationship between immunoreactive .beta.-MSH [melanotropin] and the lipotropins (LPH), the gel filtration and the immunological characteristics of .beta.-MSH were investigated in the plasma of patients with Nelson''s syndrome and Addison''s disease and in the culture medium from a human corticotropic adenoma using a sensitive radioimmunoassay from human .beta.-MSH. When added to hormone free plasma or to a plasma from a patient with Nelson''s syndrome, all the human .beta.-MSH (h.beta.-MSH) eluted from a Sephadex G-50 column as a single peak in a volume corresponding to its MW. Plasma .beta.-MSH in 3 patients with Nelson''s syndrome and 1 patient with Addison''s disease almost completely eluted in a volume corresponding to a MW range of 6000-10,000. No .beta.-MSH could be detected in its normal elution volume. Drastic pH change (8.2-2.3) did not significantly alter the elution pattern. Chromatography of a corticotropic adenoma culture medium gave a similar pattern of .beta.-MSH with a main peak in the MW range of 6000-10,000. In this radioimmunoassay the culture medium and purified h.beta.-LPH gave parallel displacement curves for [125I]h.beta.-MSH. h.beta.-LPH or a closely related substance may be the main material responsible for .beta.-MSH immunoreactivity.