Erythrocyte vesiculation: a self-protective mechanism?
Previous studies demonstrated that 20% of haemoglobin is lost from circulating erythrocytes during their total lifespan by vesiculation. To study whether removal molecules other than membrane-bound haemoglobin were present in erythrocyte-derived vesicles, flow cytometry and immunoblot analysis were employed to examine the presence of phosphatidylserine (PS) and IgG, and senescent cell antigens respectively. It was demonstrated that 67% of glycophorin A-positive vesicles exposed PS, and that half of these vesicles also contained IgG. Immunoblot analysis revealed the presence of a breakdown product of band 3 that reacted with antibodies directed against senescent erythrocyte antigen-associated band 3 sequences. In contrast, only the oldest erythrocytes contained senescent cell antigens and IgG, and only 0.1% of erythrocytes, of all ages, exposed PS. It was concluded that vesiculation constitutes a mechanism for the removal of erythrocyte membrane patches containing removal molecules, thereby postponing the untimely elimination of otherwise healthy erythrocytes. Consequently, these same removal molecules mediate the rapid removal of erythrocyte-derived vesicles from the circulation.
Willekens
Frans L A
FL
Department of Clinical Chemistry, Rijnstate Hospital, Arnhem, The Netherlands. fwillekens@alysis.nl
Werre
Jan M
JM
Groenen-Döpp
Yvonne A M
YA
Roerdinkholder-Stoelwinder
Bregt
B
de Pauw
Ben
B
Bosman
Giel J C G M
GJ
D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism; D018958:CD55 Antigens / Q000097:blood; D018957:CD59 Antigens / Q000097:blood; D002458:Cell Fractionation / Q000379:methods; D004905:Erythrocyte Aging / Q000502:physiology*; D004910:Erythrocyte Membrane / Q000502:physiology*; D006021:Glycophorins / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D010718:Phosphatidylserines / Q000097:blood
D001457:Anion Exchange Protein 1, Erythrocyte; D018958:CD55 Antigens; D018957:CD59 Antigens; D006021:Glycophorins; D007074:Immunoglobulin G; D010718:Phosphatidylserines; C051590:CD59 protein, human