Abstract
In order to detect the presence of activated platelets in vivo, platelet factor 4 (PF 4) in the platelet-free plasma was measured by radioimmunoassay in healthy subjects and diabetics with various vascular complications such as retinopathy (Scott III-V), nephropathy, ischemic heart disease and ischemic cerebral attack.
Plasma concentration of PF4 in 16 healthy subjects was 8±2 ng/ml (M±SD, range 5∼11 ng/ml). No close correlation was observed between plasma PF 4 and platelet PF 4 levels.
Thirteen of 43 patients with diabetes and vascular complications had higher PF 4 levels than 20 ng/ml. Plasma PF 4 level was examined repeatedly in 7 patients without anti-platelet therapy. Among three patients with elevated plasma PF 4 two showed continuously high PF 4 levels. PF 4 value of remaining 4 patients stayed in normal range.
Correlation coefficient between plasma PF 4 and beta-thromboglobulin (βTG) level measured by radioimmunoassay in normal subjects and diabetics were 0.76 and 0.78, respectively. In 9 out of 84 determinations high plasma βTG level was observed without elevation of PF 4 value. The opposite phenomenon was obtained in 8 determinations.
Although the raised plasma PF 4 levels are observed also in careless preparation of platelet free plasma, the measurement of PF 4 is useful for the study of platelet pathophysiology.
