title: Identification of rat prostatic steroid binding protein (PSBP) as an immunosuppressive factor.
abstract: Prostatic steroid binding protein (PSBP) is the major protein produced ( approximately 20% of the total cytosolic protein) and secreted into the seminal fluid by the rat ventral prostate but its physiological function has not been elucidated yet. Since PSBP is secreted into the seminal fluid (which is itself a potent immunosuppressor) and has strong homology with uteroglobin (which possess an important anti-inflammatory function) our aim was to determine what effect, if any, PSBP would have on the immune system. With that purpose in mind we performed mononuclear cell cultures in the presence or absence of purified PSBP and analysed the effect of this protein on different functional parameters. PSBP inhibits the mitogen-induced proliferation of normal rat spleen mononuclear cells (MNC) specifically and in a dose-dependent manner. It reduces the production of IL-2 and the expression of its receptor (analysed by flow cytometry) which are important events for lymphocyte proliferation. Also, PSBP was able to inhibit OVA-specific proliferation of lymph node cells from previously primed animals. The immunosuppressive effect of PSBP is not due to an inherent toxic effect to the cells, since the cell viability was kept intact at the different times of culture studied. We also analysed the effect of rat PSBP on mitogen-induced proliferation of mouse spleen and human blood MNC. The proliferation was strongly abolished in a dose-dependent and non-species specific fashion. Moreover, PSBP strongly inhibits the human mixed lymphocyte reaction. Taken together, the present data support evidence for a new type of function for PSBP. We report that PSBP is a potent immunosuppressor factor and we describe its effect on the immune function in vitro. Here, we discuss the possible implications of these findings in the protection of sperm from immunologic damage in the feminine reproductive tract.
authors.affiliation: Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas. Universidad Nacional de Córdoba, 5000, Cordoba, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Maccioni
authors.forename: C M
authors.initials: CM
authors.lastname: Riera
authors.forename: V E
authors.initials: VE
authors.lastname: Rivero
mesh_terms: D000727:Androgen-Binding Protein / Q000276:immunology / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D000941:Antigens / Q000008:administration & dosage; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000302:isolation & purification / Q000494:pharmacology*; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects; D007959:Lymphocyte Culture Test, Mixed; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008934:Mitogens / Q000494:pharmacology; D010047:Ovalbumin / Q000276:immunology; D049488:Phosphatidylethanolamine Binding Protein; D011467:Prostate / Q000276:immunology*; D060789:Prostatein; D051381:Rats; D017208:Rats, Wistar; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D060765:Secretoglobins; D013094:Spermatozoa / Q000276:immunology; D014598:Uteroglobin; D060788:Mammaglobin B
chemical_list: D000727:Androgen-Binding Protein; D000941:Antigens; D007166:Immunosuppressive Agents; D007376:Interleukin-2; D008934:Mitogens; D010047:Ovalbumin; D049488:Phosphatidylethanolamine Binding Protein; D060789:Prostatein; D015375:Receptors, Interleukin-2; D060765:Secretoglobins; D014598:Uteroglobin; C511482:PEBP1 protein, human; C511484:Scgb1d2 protein, rat; C511483:Scgb1d4 protein, rat; C556468:Scgb2a1 protein, rat; D060788:Mammaglobin B