Prolactin receptor gene expression in rat splenocytes and thymocytes from birth to adulthood

Abstract

In vivo and in vitro studies have indicated that the anterior pituitary hormone prolactin (PRL) is an immunoregulator and functions in the development of the neonatal immune system. In this study, prolactin receptor (PRL-R) expression from birth to adulthood as well as the effect of milk ingestion on the PRL-R expression were examined in splenocytes and thymocytes of neonatal rats. Three approaches were taken to measure PRL-R expression: (i) polymerase chain reaction (RT-PCR); (ii) antibody to PRL-R and Western blotting; (iii) antibody to PRL-R and flow cytometry. RT-PCR analysis revealed the short and long form of PRL-R mRNA in both spleen and thymus at every age tested. However, the long form of PRL-R mRNA was always more abundant than that of the short form. In addition, antipeptide antibody against the long form of PRL-R recognized 84 and 42 kD proteins in the spleen, but only the 84 kD protein in the thymus. A monoclonal antibody U6 recognized 38 and 40 kD proteins in both the spleen and thymus. Although the mRNA level of PRL-R was relatively low at birth and increased with age in both the spleen and thymus, the levels of protein bands detected with both antibodies correlated with development in the spleen; whereas the levels remained steady in the thymus. Therefore, we concluded that the expression of PRL-R at the protein level is developmentally regulated in the spleen but not in the thymus. Finally. milk ingestion in the first seven hours decreased the percentage of cells expressing cell surface PRL-R, suggesting that milk-borne PRL may have a direct effect on lymphocytes.

Prolactin Levels Correlate with Abnormal B Cell Maturation in MRL and MRL/lpr Mouse Models of Systemic Lupus Erythematosus-Like Disease

“…These antibodies form immune complexes that are deposited in the kidneys and may result in proteinuria and kidney failure. The presence of these autoantibodies indicates abnormalities in the activation and development of B cells [15, 16] and both B and T cells express the PRL receptor and secrete PRL [4, 17, 18]. SLE affects women of reproductive age at a 9 : 1 ratio compared to men and this gender bias has been attributed to the immunostimulatory properties of hormones.…”

Increased levels of prolactin receptor expression correlate with the early onset of lupus symptoms and increased numbers of transitional-1 B cells after prolactin treatment

“…These antibodies form immune complexes that are deposited in the kidneys and may cause proteinuria and kidney failure. The presence of these autoantibodies indicates abnormalities in the activation and development of B cells [12,13], and both B and T cells express the PRL receptor and produce and secrete PRL [1,14-16]. SLE mainly affects women of the reproductive age at a ratio of 9:1 compared to men, and this gender bias has been attributed to the immunostimulatory properties of hormones.…”