Immunomodulating Effects Depend on Prolactin Levels in Patients with Hyperprolactinemia

Area of Science:

• Immunology
• Endocrinology

Background:

• Prolactin influences immune cells via prolactin receptors.
• Chemokines shape T helper (Th) cell responses.
• Hyperprolactinemia (elevated prolactin) may impact immune function.

Purpose of the Study:

• To investigate the association between non-pregnancy related hyperprolactinemia and circulating levels of chemokines and immunological markers.
• To assess potential dose-dependent effects of prolactin on immune responses.

Main Methods:

• Cross-sectional study comparing 35 hyperprolactinemia patients with 102 healthy controls.
• Assessed serum levels of Th1, Th2, Th17 chemokines (CCL22, CXCL1), B cell chemokine (CXCL13), C-reactive protein, and immunoglobulins.
• Utilized an in vitro model to evaluate prolactin's effect on T-helper cell activation.

Main Results:

• Hyperprolactinemia group showed significantly higher levels of CCL22, CXCL1, CXCL13, and C-reactive protein compared to controls.
• These markers positively correlated with prolactin levels.
• Differences were observed at low/moderate hyperprolactinemia but not at high levels (>3600 mU/l).
• In vitro studies indicated prolactin increased T-helper cell activation at moderate levels but decreased it at high levels.

Conclusions:

• Hyperprolactinemia exhibits immunomodulatory effects, increasing Th2/Th17-associated chemokines and B cell attraction markers.
• A threshold effect exists, with very high prolactin levels not showing these elevations.
• In vitro data suggest a biphasic effect of prolactin on T-helper cell activation, potentially explaining the in vivo findings.