Prolactin Synthesized and Secreted by Human Peripheral Blood Mononuclear Cells: An Autocrine Growth Factor for Lymphoproliferation

• Published in: Proceedings of the National Academy of Sciences - PNAS 1992-08, Vol.89 (16), p.7713-7716
• Main Authors: Sabharwal, P., Glaser, R., Lafuse, W., Varma, S., Liu, Q., Arkins, S., Kooijman, R., Kutz, L., Kelley, K. W., Malarkey, W. B.
• Format: Article
• Language: English
• Subjects: Analysis of the immune response. Humoral and cellular immunity; Antiserum; Base Sequence; Biological and medical sciences; Blood; Blotting, Southern; Blotting, Western; Cell Line; Cell lines; Cellular biology; Complementary DNA; DNA - blood; DNA - genetics; DNA - isolation & purification; DNA Replication; Enzyme-Linked Immunosorbent Assay; Exons; Female; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Gels; Growth Substances - biosynthesis; Hormones; Humans; Immune Sera; Immunobiology; Leukocytes, Mononuclear - physiology; Lymphatic system; Lymphocytes; Lymphocytes - immunology; Medical research; Messenger RNA; Miscellaneous; Molecular Sequence Data; Molecules; Oligodeoxyribonucleotides; Placenta; Placenta - physiology; Polymerase chain reaction; Polymerase Chain Reaction - methods; Pregnancy; Prolactin - biosynthesis; Prolactin - blood; Prolactin - genetics; Regulatory factors and their cellular receptors; RNA, Messenger - analysis; RNA, Messenger - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.89.16.7713

Prolactin has been shown to have an immunoregulatory role in the rodent immune response. A prolactin-like molecule has also been found in mouse splenocytes and a human B-lymphoblastoid cell line. We have evaluated whether human peripheral blood mononuclear cells (PBMCs) synthesize and/or secrete prolactin. We used the polymerase chain reaction (PCR) to generate a 276-base-pair prolactin product from human PBMCs, and Southern blot analysis confirmed that it was related to prolactin. Western blotting using a polyclonal antibody to prolactin indicated that cell extracts prepared from human PBMCs contained a high molecular mass (60-kDa) immunoreactive prolactin. To determine whether this PBMC prolactin was being secreted, we developed a highly sensitive and specific hormonal enzyme-linked immunoplaque assay. With this assay, we were able to detect human prolactin secretion from concanavalin A (Con A)- or phytohemagglutinin-stimulated PBMCs but not from unstimulated PBMCs. We next sought to determine whether this secreted prolactin could function as an autocrine growth factor in lymphoproliferation. We observed that anti-human prolactin antiserum significantly inhibited human PBMC proliferation in response to Con A or phytohemagglutinin. We conclude that a prolactin-like molecule is synthesized and secreted by human PBMCs and that it functions in an autocrine manner as a growth factor for lymphoproliferation.