Summary
B16 mouse melanoma cell lines (B16F1, B16F10 and B16BL6) were able to induce platelet
aggregation, and concomitant release of ATP in heparinized platelet-rich plasma (PRP).
In citrated PRP, these tumor cells did not induce platelet aggregation. Addition of
heparin to citrated PRP enabled these tumor cells to induce aggregation. In heparinized
PRP, platelet aggregates induced by B16F10 cells were dissociated by the addition
of either 4 mM EDTA, 10 mM CaCl2 or 0.1 μg/ml protamine sulfate. B16F10-induced aggregation in heparinized PRP was
inhibited by preincubation with anti-fibronectin antibody, but not with antifibrinogen
or anti-von Willebrand factor antibodies. B16F10 cells induced aggregation in washed
platelet suspension with the addition of heparinized platelet-poor plasma (PPP). Cryoprecipi-tate
from human plasma showed the same effect in the presence of heparin if substituted
for PPP. The mixture of purified fibronectin, von Willebrand factor, fibrinogen and
heparin were less effective than cryoprecipitate on B16F10-induced aggregation of
washed platelets. The results suggest that an interaction between fibronectin and
heparin may be important in tumor cell-induced aggregation.
Keywords
Platelet aggregation - Tumor cell - Heparin - Fibronectin
