Description:
<jats:p><jats:bold>Background</jats:bold> Prolactin represents a stimulatory link between the neuroendocrine and immune systems, but its involvement in the neurohumoral adaptations to heart failure (HF) has not been explored.</jats:p><jats:p><jats:bold>Methods</jats:bold> We prospectively studied 55 patients (45 males, 10 females, age 48 ± 7 years) with NYHA Class II/III HF due either to dilated cardiomyopathy (CMP) (<jats:italic>n</jats:italic> = 33) or ischemic heart disease (IHD) (<jats:italic>n</jats:italic> = 22). Serum prolactin levels were determined by radioimmunoassay, soluble interleukin‐2 receptor (sIL‐2R) levels by enzyme‐linked immunoassay and HLA‐DQ genotyping with PCR. Left ventricular ejection fraction (LVEF) and end‐diastolic diameter (LVEDd) were assessed echocardiographically.</jats:p><jats:p><jats:bold>Results</jats:bold> Hyperprolactinaemia (17·3 ± 4 ng mL<jats:sup>−1</jats:sup>[Group I] vs. 4·64 ± 2 ng mL<jats:sup>−1</jats:sup>[Group II], <jats:italic>P</jats:italic> < 0·01) was found in 14 patients (8 with IHD, 6 with CMP). The distribution of HLA‐DQB1 alleles was compared in the two groups and showed a significant increase in the frequency of *0301 (86% in Group I vs. 45% in Group II, <jats:italic>P</jats:italic> < 0·05). Histidine at position 30 of the HLA‐DQB1 gene was found in 22% of Group II but in none of Group I patients. Furthermore, there was an inverse correlation between the presence of histidine at position 30 and the levels of serum prolactin. Both sIL‐2R levels, a marker of T‐cell activation, and concanavalin A‐stimulated lymphocyte proliferation were lower in Group I patients (561 ± 106 vs. 804 ± 109 pg mL<jats:sup>−1</jats:sup> and 20·8 ± 4 vs. 37·3 ± 5 cpmX10<jats:sup>3</jats:sup>[<jats:sup>3</jats:sup>H] thymidine, respectively). LVEF was significantly higher (32 ± 5%) and LVEDd smaller (62·0 ± 6 mm) in Group I compared to Group II (25 ± 4% and 68·0 ± 5 mm, respectively, <jats:italic>P</jats:italic> < 0·01) patients.</jats:p><jats:p><jats:bold>Conclusion</jats:bold> Hyperprolactinaemia presents in 25% of patients with HF and may reflect decreased activation of T‐lymphocytes associated with relatively preserved LV systolic function which is under immune‐genetic control at the HLA‐DQ locus.</jats:p>