Prolactin deficiency in rheumatoid arthritis

Area of Science:

• Endocrinology
• Immunology
• Rheumatology

Background:

• Rheumatoid arthritis (RA) is a chronic autoimmune disease.
• Hormonal imbalances, including prolactin (PRL) dysfunction, may play a role in RA pathogenesis.
• Previous studies have yielded conflicting results regarding PRL levels in RA patients.

Purpose of the Study:

• To investigate the bioactivity and immunoactivity of circulating prolactin (PRL) in patients with rheumatoid arthritis (RA).
• To compare PRL levels and function between RA patients and healthy controls.
• To explore the relationship between PRL status and clinical features of RA, such as anemia.

Main Methods:

• Sera from 48 RA patients and 23 controls were analyzed.
• Radioimmunoassay (RIA) was used to measure immunoactive PRL levels.
• Nb2 lymphoma cell proliferation bioassay was employed to assess PRL bioactivity.

Main Results:

• RA patients exhibited significantly diminished PRL bioactivity compared to controls, despite near-normal immunoactive PRL levels.
• A subset of male RA patients showed lower serum PRL levels by RIA.
• PRL bioactivity in RA patients with anemia and high reticulocyte counts was elevated, while those with low reticulocyte counts showed decreased bioactivity.
• Isolated PRL from RA patients' sera demonstrated reduced bioactivity.

Conclusions:

• Rheumatoid arthritis is associated with a deficiency in prolactin bioactivity.
• The discrepancy between immunoactive and bioactive PRL suggests post-translational modification or inhibitory serum factors in RA.
• PRL dysfunction may contribute to the pathophysiology of rheumatoid arthritis.