High-affinity binding sites for heparin generated on leukocytes during apoptosis arise from nuclear structures segregated during cell death.
During cell death of human cultured leukocytes (Jurkat, HL-60, THP-1, U937) and freshly prepared leukocytes, we observed a greater than 100-fold increase in the affinity of apoptotic and necrotic cells for fluorescein isothiocyanate (FITC)-heparin in comparison with live cells. Binding of FITC-heparin was reversed in the presence of high ionic strength, unlabeled heparan sulfate, and heparin and pentosan polysulfate, but not in the presence of chondroitin and dermatan sulfates. During the course of cell death, the increase in the percentage of cells positive for annexin V binding correlated with the increase in the population positive for binding FITC-heparin. Confocal microscopy demonstrated that heparin binding to dead cells was restricted to 1 or 2 small domains on the surfaces of apoptotic cells and to larger, but still discrete, areas that did not localize with chromatin on ruptured necrotic cells. The heparin-binding domains originated from the nucleus and may correspond to the ribonucleoprotein-containing structures that have recently been shown to segregate within the nucleus of cells and to move onto the cell membrane. We observed that phagocytosis of dead Jurkat cells by monocyte-derived macrophages was blocked when the heparin-binding capacity of the dead cells was saturated by the addition of pentosan polysulfate. From this we concluded that the ability of dead cells to bind to heparan sulfate proteoglycans on the surfaces of macrophages may assist in phagocytic clearance.
Gebska
Milena A
MA
Coagulation and Fibrinolysis Laboratory, Thrombosis Research Institute, Emmanuel Kaye Building, 1B Manresa Road, Chelsea, London SW3 6LR, UK.
Titley
Ian
I
Paterson
Hugh F
HF
Morilla
Ricardo M
RM
Davies
Derek C
DC
Gruszka-Westwood
Alicja M
AM
Kakkar
Vijay V
VV
Eccles
Suzanne
S
Scully
Michael F
MF
D017209:Apoptosis; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D022003:Cell Nucleus Structures / Q000378:metabolism*; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism / Q000502:physiology; D006493:Heparin / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D007962:Leukocytes / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D008264:Macrophages / Q000737:chemistry / Q000502:physiology; D018613:Microscopy, Confocal; D009336:Necrosis; D010587:Phagocytosis / Q000187:drug effects; D014407:Tumor Cells, Cultured
D019812:Heparan Sulfate Proteoglycans; D006493:Heparin