Evaluation of a Semi-micro Method for Measuring Platelet Aggregation in Whole Blood Samples

Summary

Platelet aggregation has been measured rapidly and simply in 0.5 ml samples of citrated whole blood, by counting the unaggregated platelets remaining after the samples were mixed with aggregating agents, and the erythrocytes rapidly sedimented by adding physiological saline. Concentration-dependent aggregation responses were obtained with adenosine diphosphate, glass beads, serotonin and connective tissue. Aggregation induced by mixing alone was also measured.

The aggregation responses were altered by minor changes in citrate concentration, and increased during the first hour after venepuncture. In heparinised blood samples, platelet counts were reduced and all aggregation responses substantially increased. Extending the time interval between aggregating stimulus and platelet counting had no significant effect on the aggregation responses. The main source of technical error was sampling for platelet counts, and the variablility was inversely related to the size of micropipette used. Results of tests in volunteers established the normal range of responses to aggregating agents, and showed that blood samples taken weeks apart from the same subject gave more variable responses than did samples taken an hour apart.

• References

• 1 Aster R.H, and Jandl J. H. 1964; Platelet sequestration in man. Journal of Clinical Investigation 43: 843.
• 2 Baumgartner H. R, and Born G. V. R. 1969; The relation between the 5-hydroxytryptamine content and aggregation of rabbit platelets. Journal of Physiology 201: 397.
• 3 Bergman I, and Loxley R. 1963; Two improved and simplified methods for the spectrophotometry determination of hydroxyproline. Analytical Chemistry 35: 1961.
• 4 Born G. V. R. 1962; Quantitative investigations into the aggregation of blood platelets. Journal of Physiology (London) 162: 67P.
• 5 Born G. V. R, and Hume M. 1967; Effects of the numbers and sizes of platelet aggregates on the optical density of plasma. Nature (London) 215: 1027.
• 6 Caspary E.A, Prineas J, Millar W, and Field E. J. 1967; Platelet stickiness in multiple sclerosis. British Medical Journal 1: 610.
• 7 Chesney C, McL Harper E, and Colman R. W. 1972; Critical role of the carbohydrate side chains of collagen in platelet aggregation. Journal of Clinical Investigation 51: 2693.
• 8 Constantine J. W. 1965; Temperature and the aggregation of rabbit platelets by adenosine diphosphate. Nature (London) 205: 1075.
• 9 Friedberg N. M, and Zucker M. B. 1972; ADP as a cause of reversible inhibition of platelet retention in glass-bead columns. Journal of Laboratory and Clinical Medicine 80: 603.
• 10 Gordon J. L, and Gresham G. A. 1972; The measurement of platelet aggregation in small blood samples. Atherosclerosis 15: 383.
• 11 Hardisty R. M, Dormandy K.M, and Hutton R.A. 1964; Thrombasthenia. Studies on three cases. British Journal of Haematology 10: 371.
• 12 Hardisty R. M, and Hutton R.A. 1967; Bleeding tendency associated with ‘new’ abnormality of platelet behaviour. Lancet 1: 983.
• 13 Hardisty R. M, Hutton R. A, Montgomery D, Richard S, and Trebilcock H. 1970; Secondary platelet aggregation: a quantitative study. British Journal of Haematology 19: 307.
• 14 Harrison M. J. G, Emmons P. R, and Mitchell J. R. A. 1966; The effect of white cells on platelet aggregation. Thrombosis et Diathesis Haemorrhagica 16: 105.
• 15 Harrison M. J. G, and Mitchell J. R. A. 1966; The influence of red blood cells on platelet adhesiveness. Lancet 2: 1163.
• 16 Hellem A. J. 1960; The adhesiveness of human blood platelets in vitro. . Scandinavian Journal of Clinical and Laboratory Investigation, 12, Suppl 51: 1.
• 17 Hellem A. J. 1971; Adenosinediphosphate-induced platelet adhesiveness in diabetes mellitus with complications. Acta Medica Scandinavica 190: 291.
• 18 Hirsh J, Castelan D. J, and Loder P. B. 1967; Spontaneous bruising associated with a defect in the interaction of platelets with connective tissue. Lancet 2: 18.
• 19 Hirsh J, and McBride J. A. 1965; Increased platelet adhesiveness in recurrent venous thrombosis and pulmonary embolism. British Medical Journal 2: 797.
• 20 Holdrinet A. E, Wals M, and Haanen C. 1967; Increase in platelet aggregation with time after venepuncture. Lancet 2: 893.
• 21 McDonald L, and Edcill M. 1957; Coagulability of the blood in ischaemic heart disease. Lancet 2: 457.
• 22 O’Brien J. R. 1964; Variability in the aggregation of human platelets by adrenaline. Nature (London) 202: 1188.
• 23 O’Brien J. R. 1969; Platelet aggregation tests and thrombosis. Journal of the Royal College of Physicians (London) 3: 193.
• 24 O’Brien J. R, and Heywood J. B. 1967; Some interactions between human platelets and glass: von Willebrand’s disease compared with normal. Journal of Clinical Pathology 20: 56.
• 25 Rogers A. B. 1972; The effect of pH on human platelet aggregation induced by epinephrine and ADP. Proceedings of the Society for experimental Biology and Medicine 139: 1100.
• 26 Rozenberg M. C, and Firkin B. G. 1965; The rate of platelet aggregation in haemorrhagic disease and thrombosis. Scandinavian Journal of Haematology 3: 5.
• 27 Salzman E. W. 1963; Measurement of platelet adhesiveness. A simple in vitro technique demonstrating an abnormality in von Willebrand’s diesease. Journal of Laboratory and Clinical Medicine 62: 724.
• 28 Shaper A. G. 1968; Platelet function. Lancet 1: 642.
• 29 Vreeken J, and Van Aken W. G. 1971; Spontaneous aggregation of blood platelets as a cause of idiopathic thrombosis and recurrent painful toes and fingers. Lancet 2: 1394.
• 30 Wright H. P. 1942; Changes in the adhesiveness of blood platelets following parturition and surgical operations. Journal of Pathology and Bacteriology 54: 461.