Expression of prolactin and its receptor in human lymphoid cells.

Abstract

We have investigated whether human lymphoid cells are able to synthesize and secrete human PRL (hPRL) and to express PRL receptors. Metabolic labeling with [35S]methionine and immunoprecipitation of cell extracts from human mononuclear cells (MNC) and a human T lymphocyte cell line with an antiserum against hPRL revealed protein of M(r) 23,000, identical in size to pituitary hPRL. Dilution curves of lymphocyte immunoreactive hPRL were parallel to those obtained with pituitary hPRL in an immunoradiometric assay using two monoclonal antibodies against hPRL. Polymerase chain reaction experiments with primers located in the coding sequence of hPRL showed that the hPRL gene was expressed in MNC. Furthermore, cDNA cloning and sequence analysis indicated the presence of an extra 5' noncoding exon previously described for decidual hPRL. When MNCs were further separated into B cells, T cells, and monocytes, the expression of hPRL appeared to be mainly associated with the T lymphocyte fraction. The hPRL transcript was also detected in thymocytes and in a set of human lymphoid cell lines. Finally, polymerase chain reaction experiments revealed a ubiquitous distribution of PRL receptor gene expression in B cells, T cells, and monocytes. The presence of the receptor for PRL and production of PRL by T lymphocytes suggest a possible autocrine or paracrine effect of PRL in immune cell function.

Rat prolactin synthesis by lactating mammary epithelial cells

“…In lymphoid cells, in addition to the 23-kDa form, a 36-kDa form has been described as newly synthesized PRL [5]. However, in these cells as in present work, radioactive molecules not immunologically related to PRL were also observed after immunoprecipitation.…”

“…It can be postulated that lactating MEC are also able to synthesize a glycosylated form. Moreover, synthesis of PRL as a 23-kDa form by lymphoid cells has been reported [5]. In the hypothalamic-neurohypophyseal system, synthesis of the 23-kDa form of PRL and its processing into a 14-kDa fragment has also been described [4].…”

“…Prolactin (PRL), first discovered in the pituitary gland, is now thought to be produced in a variety of mammalian tissues [1][2][3][4][5]. The PRL mRNA has been observed in several cell types [6][7][8][9], including mammary epithelial cells (MEC) of lactating rat, goat, sheep and rabbit [10][11][12][13] and of normal and neoplastic tissue [14].…”

EGF stimulates Pit-1 independent transcription of the human prolactin pituitary promoter in human breast cancer SK-BR-3 cells through its proximal AP-1 response element

“…In addition to the pituitary gland, synthesis of PRL mRNA has been observed in T lymphocytes and decidualized endometrium (DiMattia et al, 1988;Gellersen et al, 1989;Pellegrini et al, 1992). Moreover, PRL mRNAs have also been detected in human mammary tissues (Fields et al, 1993;Clevenger et al, 1995;Reynolds et al, 1997).…”

Rapamycin, FK506 and cyclosporin A inhibit human prolactin gene expression

“…Administration of antisera to prolactin affects the development of T-lymphocytes in the thymus and the spleen [7]. T-lymphocytes express both prolactin and prolactin receptors [8]. In view of this immunoregulatory role of prolactin we decided to investigate whether immunosuppressants could influence pituitary prolactin gene expression.…”