Summary
Some patients with clinical evidence of atherosclerosis and others with diabetes were
compared with appropriate controls. The intraplatelet level of platelet factor 4 (PF4)
was significantly decreased in the arteriopaths and was lower in the diabetics when
compared with controls. Patients with transient ischaemic attacks and stroke have
even lower values.
Intravenous heparin liberates large amounts of PF4 from an unknown reservoir, perhaps
the endothelium, into the plasma. Arteriopaths liberated significantly more PF4 than
the controls and the diabetics most. If a second heparin injection is given 24 hr
after the first, the resultant plasma PF4 level was on average half that achieved
after the first injection and again the patients had higher levels than the controls.
Thus the reservoir originally “emptied” of PF4 by the heparin had been partially refilled
in 24 hr and the reservoir in the atherosclerotic patients then contained more than
the controls. Patients with atherosclerosis and especially diabetics differ from controls
in the PF4 content of their platelets and in their response to heparin and in the
rate of refill of the “heparin-mobilisable pool of PF4”.
Keywords
Intra-platelet PF4 - PF4 heparin response - Atherosclerosis - Diabetes - Transient
ischaemic attacks
