title: Role of glycoprotein Ibalpha in phagocytosis of platelets by macrophages.
abstract: BACKGROUND
  Platelet (PLT) storage at 0 to 4 degrees C suppresses bacterial multiplication, but induces clusters of glycoprotein (GP) Ibalpha that trigger their phagocytosis by macrophages and reduce their survival after transfusion. A method was sought that detects cold-induced changes in GPIbalpha involved in phagocytosis.
  
  
  METHODS
  Human PLTs were isolated and stored for up to 48 hours at 0 degrees C. Binding of a phycoerythrin (PE)-labeled antibody directed against amino acids (AA) 1-35 on GPIbalpha (AN51-PE) was compared with phagocytosis of PLTs by matured monocytic THP-1 cells, analyzed by fluorescence-activated cell sorting.
  
  
  RESULTS
  Freshly isolated PLTs were detected as a single population of AN51-PE-positive particles and showed less than 5 percent phagocytosis. Cold storage led to a decrease in AN51-PE binding and an increase in phagocytosis. N-Acetylglucosamine, known to interfere with macrophage recognition of GPIbalpha clusters, restored normal AN51-PE binding to cold-stored PLTs and suppressed phagocytosis.
  
  
  CONCLUSIONS
  It is concluded that binding of an antibody against AA 1-35 on GPIbalpha reflects changes in GPIbalpha that make PLTs targets for phagocytosis by macrophages.
authors.affiliation: Thrombosis and Haemostasis Laboratory, DCCH, the Department of Immunology, UMC-Utrecht, the Institute for Biomembranes Utrecht University, and the Sanquin Blood Bank Region North-West, Utrecht, the Netherlands.
authors.forename: Bahram A
authors.initials: BA
authors.lastname: Badlou
authors.forename: Gerrit
authors.initials: G
authors.lastname: Spierenburg
authors.forename: Hans
authors.initials: H
authors.lastname: Ulrichts
authors.forename: Hans
authors.initials: H
authors.lastname: Deckmyn
authors.forename: W Martin
authors.initials: WM
authors.lastname: Smid
authors.forename: Jan-Willem N
authors.initials: JW
authors.lastname: Akkerman
mesh_terms: D000117:Acetylglucosamine / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001792:Blood Platelets / Q000502:physiology*; D005374:Filtration; D006801:Humans; D008264:Macrophages / Q000276:immunology*; D010587:Phagocytosis; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000502:physiology*
chemical_list: D000911:Antibodies, Monoclonal; D019038:Platelet Glycoprotein GPIb-IX Complex; D000117:Acetylglucosamine