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.…”

The prolactin receptor: A cross‐species comparison of gene structure, transcriptional regulation, tissue‐specificity, and genetic variation

“…In rodents, Prlr ‐LF and ‐SF are expressed in a variety of immune‐modulating tissues including the thymus, bone marrow, spleen, and lymph node. More specifically, B cells and macrophages from spleen, lymph nodes and peripheral blood, as well as T cells from the thymus all express PRLR 121–123 . Within the splenic B‐cell population of mice, transitional B‐cells had the highest relative level of Prlr mRNA expression compared with mature B‐cells, while among mature B‐cell subsets, marginal B‐cells had an approximately two‐fold higher expression of Prlr than follicular B‐cells 124 .…”

“…More specifically, B cells and macrophages from spleen, lymph nodes and peripheral blood, as well as T cells from the thymus all express PRLR. [121][122][123] Within the splenic B-cell population of mice, transitional B-cells had the highest relative level of Prlr mRNA expression compared with mature B-cells, while among mature B-cell subsets, marginal B-cells had an approximately two-fold higher expression of Prlr than follicular B-cells. 124 In chickens, PRLR are expressed in the bursa of Fabricus follicles, thymus lobules, and throughout the splenic pulp, while the expression of PRLR-LF and -SF in bovine lymphocytes was altered in response to photoperiod and bromocriptine-induced hypoprolactinemia.…”