Serum prolactin levels and prolactin mRNA expression in peripheral blood mononuclear cells in hepatitis C virus infection

Prolactin is not only a pituitary hormone but an immunoregulatory hormone secreted from lymphocytes. Prolactin induction in relation to hepatitis C virus (HCV) infection has not been elucidated. The serum levels of prolactin were examined in 232 HCV‐infected subjects positive for anti‐HCV antibody and 65 healthy controls negative for it, who were recruited in the cohort study. The prolactin mRNAs were measured in peripheral blood mononuclear cells (PBMCs) of eleven healthy volunteers including five men and six women before and after stimulation by HCV in vitro. The serum level of prolactin and prolactin mRNA in PBMCs were measured by chemiluminescence immunoassay and real‐time PCR, respectively. The serum levels of prolactin were significantly higher in the HCV‐infected subjects (median: 7.5, IQR: 5.7–10.9 ng/ml) than in the controls (median: 5.6, IQR: 4.4–8.3 ng/ml) (P