title: Immunosuppression by human seminal plasma--extracellular organelles (prostasomes) modulate activity of phagocytic cells.
abstract: OBJECTIVE
  Prostasomes are trilamellar to multilamellar vesicles produced by the acinar cells of the human prostate and are present in appreciable amounts in normal human semen. The aim of this work was to study the effect of prostasomes on human polymorphonuclear cell and monocyte function.
  
  
  METHODS
  Functional activity of human neutrophils and monocytes was studied after incubation with prostasomes isolated from normal human seminal plasma. The following functional tests were employed: ability to ingest latex particles and opsonized bacteria (St. aureus) and ability to generate superoxide anion in response to PMA and FMLP. The latter was determined by measuring the superoxide-dismutase inhibitable reduction of ferricytochrome c to ferrocytochrome c at 550 nm. Expression of cell surface markers and interactions of prostasomes with cells were studied by cytofluorimetry.
  
  
  RESULTS
  We show that prostasomes bind rapidly to the leukocyte cell membrane followed by internalization of adsorbed material. Interactions of prostasomes with neutrophils and monocytes inhibits their ability to phagocytose latex particles. The ability to ingest opsonized bacteria is, however, not impaired. Our results also show that incubation of leukocytes with prostasomes effectively inhibits superoxide anion generation in response to activation by PMA and FMLP.
  
  
  CONCLUSIONS
  Prostasomes may play a complementary role to other immunosuppressive factors contained in the human semen. They may protect sperm cells from deleterious effects of phagocytosing cells, prolong their life, and consequently enhance the chance of conception. At the same time prostasomes may have a permissive effect on sexually transmitted diseases.
authors.affiliation: MRC Reproductive Biology Unit, University of Edinburgh, Scotland.
authors.forename: G
authors.initials: G
authors.lastname: Skibinski
authors.forename: R W
authors.initials: RW
authors.lastname: Kelly
authors.forename: D
authors.initials: D
authors.lastname: Harkiss
authors.forename: K
authors.initials: K
authors.lastname: James
mesh_terms: D002448:Cell Adhesion; D002462:Cell Membrane / Q000276:immunology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D006801:Humans; D007108:Immune Tolerance / Q000502:physiology*; D007840:Latex / Q000378:metabolism; D007962:Leukocytes / Q000378:metabolism; D008297:Male; D009000:Monocytes / Q000502:physiology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D015388:Organelles / Q000276:immunology*; D010587:Phagocytosis / Q000502:physiology*; D011467:Prostate / Q000166:cytology*; D017463:Receptors, Complement 3b / Q000096:biosynthesis; D017452:Receptors, IgG / Q000096:biosynthesis; D012661:Semen / Q000166:cytology / Q000276:immunology*; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors
chemical_list: D007840:Latex; D017463:Receptors, Complement 3b; D017452:Receptors, IgG; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D013755:Tetradecanoylphorbol Acetate