title: Transfer of functional prostasomal CD59 of metastatic prostatic cancer cell origin protects cells against complement attack.
abstract: BACKGROUND
  Prostasomes are secretory granules produced, stored, and released, by the glandular epithelial cells of the prostate. They express the glycosylphosphatidylinositol (GPI)-anchored complement regulatory protein CD59, which has been shown to be transferred to spermatozoa and erythrocytes.
  
  
  METHODS
  The CD59 content of prostasomes isolated from seminal fluid and malignant prostate cells (PC-3, DU145, and LNCaP) and the transfer of prostasomal CD59 to rabbit erythrocytes (RE) and to PIPLC-treated and unmanipulated cancer cells were investigated using FACS. All prostasomes were also incubated with RE and tested in a hemolytic assay.
  
  
  RESULTS
  Prostasomes from cancer cells had higher expression of CD59 than those of normal cells. Prostasomal CD59 of different origin could be transferred to RE, malignant cell lines stripped of CD59 by PIPLC, or unmanipulated LNCaP cells. Malignant cell prostasomes had an increased ability to inhibit complement-mediated lysis compared to those from non-malignant cells.
  
  
  CONCLUSIONS
  These results point to a novel mechanism by which prostasomes can protect prostatic malignant cells from complement attack.
authors.affiliation: Department of Radiology, Oncology, and Clinical Immunology, Division of Clinical Immunology, The Rudbeck Laboratory C5, SE-751 85 Uppsala, Sweden.
authors.forename: Adil A
authors.initials: AA
authors.lastname: Babiker
authors.forename: Bo
authors.initials: B
authors.lastname: Nilsson
authors.forename: Gunnar
authors.initials: G
authors.lastname: Ronquist
authors.forename: Lena
authors.initials: L
authors.lastname: Carlsson
authors.forename: Kristina Nilsson
authors.initials: KN
authors.lastname: Ekdahl
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D018957:CD59 Antigens / Q000276:immunology / Q000378:metabolism*; D045744:Cell Line, Tumor; D003165:Complement System Proteins / Q000276:immunology*; D004912:Erythrocytes / Q000276:immunology* / Q000378:metabolism; D005434:Flow Cytometry; D006461:Hemolysis / Q000276:immunology; D006801:Humans; D008297:Male; D043265:Phosphatidylinositol Diacylglycerol-Lyase / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000276:immunology* / Q000556:secondary; D011817:Rabbits; D022142:Secretory Vesicles / Q000276:immunology* / Q000378:metabolism; D012661:Semen / Q000276:immunology / Q000378:metabolism
chemical_list: D000906:Antibodies; D018957:CD59 Antigens; D003165:Complement System Proteins; D043265:Phosphatidylinositol Diacylglycerol-Lyase