In vitro function and phagocytosis of galactosylated platelet concentrates after long-term refrigeration.
BACKGROUND
Short-term refrigeration of platelets (PLTs) in the absence of plasma results in their rapid clearance after transfusion. Blocking beta-N-acetylglucosamine (beta-GlcNAc) residues of glycoprotein Ibalpha (GPIbalpha) with galactose prevents binding of refrigerated human and mouse PLTs to macrophages and prolongs the circulation times of refrigerated mouse PLTs. PLT-associated galactosyltransferase efficiently galactosylates chilled PLTs in the presence of its substrate UDP-galactose is added to PLT-rich plasma.


METHODS
To characterize the hemostatic function of refrigerated and galactosylated human PLTs processed in the blood bank, PLT aggregation was studied in vitro under static and flow conditions and expression of integrin beta3 (CD61), CD62P (P-selectin), GPIbalpha (CD42b), annexin V binding, and integrin alphaIIbeta3 activation with flow cytometry. Affinity of macrophages for galactosylated refrigerated PLTs was evaluated with THP-1 cells, which recognize and phagocytize refrigerated PLTs.


RESULTS
PLTs refrigerated and galactosylated for 14 days 1) maintained their ability to aggregate when exposed to agonists in a standard aggregometry assay, 2) showed less pronounced changes in surface expression of GPIbalpha compared with room temperature (RT)-stored PLTs, 3) increased P-selectin expression, and 4) were poorly phagocytized by differentiated THP-1 cells in vitro. In addition, it is shown that refrigeration of PLTs does not affect their adhesive properties under in vitro flow conditions.


CONCLUSIONS
It is shown that refrigerated human PLTs retain in vitro function better than RT PLTs during storage and demonstrate that galactosylation prevents recognition of stored refrigerated PLTs by macrophages in vitro.
Babic
Aleksandar M
AM
Department of Pathology, Division of Translational Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
Josefsson
Emma C
EC
Bergmeier
Wolfgang
W
Wagner
Denisa D
DD
Kaufman
Richard M
RM
Silberstein
Leslie E
LE
Stossel
Thomas P
TP
Hartwig
John H
JH
Hoffmeister
Karin M
KM
D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology*; D001793:Blood Preservation / Q000379:methods*; D002448:Cell Adhesion; D048430:Cell Shape; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D005240:Feasibility Studies; D005690:Galactose / Q000494:pharmacology*; D006031:Glycosylation; D006801:Humans; D008264:Macrophages / Q000378:metabolism; D010587:Phagocytosis / Q000187:drug effects*; D012034:Refrigeration
D003094:Collagen; D005690:Galactose