Evaluation of a quantitative platelet-collagen adhesiveness test system

A method is described for the quantitative measurement of the blood platelet-collagen reaction, in which the adhesiveness of blood platelets is measured with a standard collagen suspension. Though glass has been used in many blood platelet adhesiveness tests, collagen fibers are a more biological substrate. The test, as developed, involves the mixing of a pre-determined volume of a standard collagen suspension (that which produces ∼ 50% adhesion in normal PRP) to an aliquot of platelet-rich plasma (platelet count adjusted to 400,000/mm 3), shaking with a vortex shaker for 5 seconds, and fixing immediately with glutaraldehyde fixative. The mixture is then centrifuged at 100 × g and a platelet count determined on the supernatant. Percent decrease in platelet count over blank is used as the platelet adhesiveness index. If the PRP-collagen mixture is shaken for 5 seconds but not fixed with glutaraldehyde for 30 seconds, platelet aggregation also occurs. This decreases the platelet count even further; such a measurement can be used to distinguish conditions or agents that affect aggregation but not adhesion. The method is illustrated by determinations of the effects of chlorpromazine and EDTA in vitro and aspirin in vivo , and the effect of dialysis on the adhesiveness index and platelet aggregation in uremic patients. The results indicated that chlorpromzine inhibited adhesion while EDTA did not, but EDTA inhibited the subsequent aggregation. Aspirin did not inhibit adhesion, but inhibited aggregation. The uremic patients had a very low adhesiveness index before dialysis. Dialysis improved the adhesiveness index, but it still was lower than normal. This method could be valuable both clinically and preclinically to test compounds for pharmacologic activity.