Immunoradiometric analysis of circulating human glycosylated and nonglycosylated prolactin forms: spontaneous and stimulated secretions.
The monoclonal antibodies (MAbs) obtained in mice immunized with human PRL coupled to an anti-PRL MAb were screened for their ability to distinguish the glycosylated (G-) and nonglycosylated (NG-) forms of PRL. The 431-29 MAb exhibited high affinity binding for NG-PRL but little or no cross-reactivity to G-PRL. Using this antibody in conjunction with other MAbs which equally recognized both forms, we developed 2 immunoradiometric assays which were used to determine the amount of G- and NG-PRL in plasma. In 85 normal subjects, NG-PRL baseline levels averaged 6.6 +/- 3 micrograms/L, and represented 76 +/- 8% of the total PRL immunoreactivity. In 74 pregnant women, this proportion was significantly higher during the last 2 trimesters (84 +/- 4% and 85 +/- 6%), as compared to the first trimester (76 +/- 7%). In 6 healthy volunteers studied over 24 h, 79% of the NG-PRL peaks detected using the cluster algorithm occurred concomitantly to a G-PRL peak. The mean NG-PRL/PRL ratio was significantly higher during NG-PRL pulses (81 +/- 9%) than during valleys (71 +/- 12%). Similarly, this ratio was significantly increased during TRH or metoclopramide stimulated PRL secretion (to 88 +/- 7% and 86 +/- 6%, respectively). We conclude that 1) NG-PRL is the predominant immunoassayable form of PRL in plasma; 2) both G- and NG-PRL are cosecreted but NG-PRL is the main PRL form released during spontaneous or pharmacologically induced PRL secretion.
Brue
T
T
Service d'Endocrinologie, Hôpital Nord, Marseille, France.
Caruso
E
E
Morange
I
I
Hoffmann
T
T
Evrin
M
M
Gunz
G
G
Benkirane
M
M
Jaquet
P
P
D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal; D002940:Circadian Rhythm; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D007118:Immunoassay; D015151:Immunoblotting; D015592:Immunoradiometric Assay; D008297:Male; D008787:Metoclopramide / Q000494:pharmacology; D008875:Middle Aged; D011247:Pregnancy; D011388:Prolactin / Q000031:analogs & derivatives* / Q000097:blood*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology
D000911:Antibodies, Monoclonal; C043928:prolactin, glycosylated; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D008787:Metoclopramide