The presence of macromolecular prolactin in serum of pregnant women and patients with pituitary adenoma

Abstract

The heterogeneity of immunoreactive Prolactin (IR-PRL) in serum of pregnant women and patients with pituitary adenoma were studied by Sephadex G-100 gel chromatography. The major IR-PRL peaks in serum of pregnant women were eluted at the position corresponding to that of 125I-PRL and the small amount of IR-PRL peaks were eluted near the void volume (peak 1) and between the void volume and 125I-PRL (peak 2). On the other hand, the proportion of peak 1 and peak 2 to total immunoreactivity was significantly increased in serum of patients with pituitary adenoma compared to those in serum of pregnant women. The rechromatographic studies under conditions of protein denaturation and sulfide cleavage on Sepharose CL-6B column revealed that the peak 1 of the pregnant women and patients with pituitary adenoma were eluted at the position between 125I-AFP and ovalbumine and the molecular weight was estimated to be about 54,000. This macromolecular PRL was also bound specifically to Sepharose coupled with anti-PRL, indicating that this macromolecule contained a sequence of PRL in its structure.