Summary
Granulocyte colony-stimulating factor (G-CSF) stimulates the bone marrow to produce
granulocytes and stem cells and is widely used to accelerate neutrophil recovery after
chemotherapy. Interestingly, specific G-CSF receptors have been demonstrated not only
on myeloid cells, but also on platelets. Data on the effects of G-CSF on platelet
function are limited and partly conflicting. The objective of this study was to determine
the effect of G-CSF on platelet aggregation and in vivo platelet activation. Seventy-eight, healthy volunteers were enrolled into this randomised,
placebo-controlled trial. Subjects received 5 μg/kg methionyl human granulocyte colony-stimulating
factor (r-metHuG-CSF, filgrastim) or placebo subcutaneously for four days. We determined
platelet aggregation with a whole blood impedance aggregometer with various, clinically
relevant platelet agonists (adenosine diphosphate [ADP], collagen, arachidonic acid
[AA], ristocetin and thrombin receptor activating peptide 6 [TRAP]). Filgrastim injection
significantly enhanced ADP (+40%), collagen (+60%) and AA (+75%) -induced platelet
aggregation (all p<0.01 as compared to placebo and p<0.001 as compared to baseline).
In addition, G-CSF enhanced ristocetin-induced platelet aggregation (+18%) whereas
TRAP-induced platelet aggregation decreased slightly (-14%) in response to filgrastim.
While baseline aggregation with all agonists was only slightly but insignificantly
higher in women than in men, this sex difference was enhanced by G-CSF treatment,
and became most pronounced for ADP after five days (p<0.001). Enhanced platelet aggregation
translated into a 75% increase in platelet activation as measured by circulating soluble
P-selectin. G-CSF enhances platelet aggregation and activation in humans. This may
put patients suffering from cardiovascular disease and cancer at risk for thrombotic
events.
Keywords
G-CSF - platelets - whole blood aggregometry - randomised controlled trial - gender
difference