EFFECT OF ELEVATED SERUM PROLACTIN CONCENTRATIONS ON THE IMMUNOPHENOTYPE OF HUMAN-LYMPHOCYTES, MITOGEN-INDUCED PROLIFERATION AND PHAGOCYTIC-ACTIVITY OF POLYMORPHONUCLEAR CELLS

It has been suggested that the immune system is an important target ti ssue of prolactin (PRL). We therefore investigated several immune para meters in nine patients with chronically elevated serum prolactin conc entrations. The immunophenotype of lymphocytes, mitogen-induced lympho cyte proliferation and phagocytic activity of polymorphonuclear cells were determined under high serum prolactin levels and 2 weeks after tr eatment with dopamine agonists. An increased CD4/CD8 ratio in the hype rprolactinaemic patients could be detected compared with healthy contr ol subjects, which remained high after treatment and did not seem to c orrelate with serum prolactin concentrations. Peripheral blood B lymph ocytes showed an increased expression of CD69 in the treated group but not in untreated patients compared with healthy control subjects. Int erleukin 2 receptor, CD45RO, transferrin receptor or HLA-DR expression of CD4 or CD8 cells, as well as oxidative burst and phagocytic activi ty of granulocytes, were not affected in the patients with prolactinom as. Lymphocyte transformation response to phytohaemagglutinin in vitro was found not to be influenced by elevated prolactin levels except at the highest mitogen concentration tested. These data together with pr evious reports suggest that, although PRL is required for lymphocyte m aturation to achieve normal immune function, elevated PRL levels do no t lead to an 'overstimulation' of the immune system in men.