The Effect of White Cells on Platelet Aggregation

Summary

The effect of white cells on platelet aggregation has been studied. White cells have little or no effect on nor-adrenaline induced clumping, produce disaggregation of ADP, 5HT and thrombin induced clumping, and first enhance and then reverse ATP induced clumping. The effects of white cells on clumping are similar to their effects on the clumping agents themselves, for they do not inactivate nor-adrenaline, but rapidly inactivate ADP, and produce a more active agent from ATP. In respect of the patient to patient variability in clumping activity, the amount of aggregation produced by ATP is very closely related to the white cell content of the PRCP, whereas the variations in ADP induced clumping must be due to other factors. The significance of these findings for the possible role of the platelet clumping agents in arterial thrombosis is discussed.

• References

• 1 Born G. V. R. Changes in the distribution of phosphorus in platelet rich plasma during clotting. Biochem. J 68: 695 1958;
• 2 Born G. V. R. Quantitative investigations into the aggregation of blood platelets. J. Physiol. (Lond.) 162: 67P 1962;
• 3 Brecher G, Gronkite E. P. Morphology and enumeration of human blood platelets. J. appl. Physiol 3: 365 1950;
• 4 Brent L, Medawar P. B. Tissue Transplantation: A new approach to the “typing” problem. Brit. med. J II: 269 1963;
• 5 Emmons P. R, Mitchell J. R. A. Post-operative changes in platelet clumping activity. Lancet I: 71 1965;
• 6 Emmons P. R, Harrison M. J. G, Honour A. J, Mitchell J. R. A. Effect of dipyridamole on human platelet behaviour. Lancet II: 603 1965;
• 7 Gaarder A, Jonson J, Laland S, Hellem A. J, Owren P. A. Adenosine diphosphate in red cells as a factor in the adhesiveness of human blood platelets. Nature (Lond.) 192: 531 1961;
• 8 Harrison M. J. G, Emmons P. R, Mitchell J. R. A. The effect of enzyme inhibitors on platelet aggregation in vitro. Thrombos. Diathes. haemorrh. (Stuttg.) (In press)
• 9 Haslam R. J. Role of adenosine diphosphate in the aggregation of human blood platelets by thrombin and by fatty acids. Nature (Lond.) 202: 765 1964;
• 10 Henry R. L. Leucocytes and thrombosis. Thrombos. Diathes. haemorrh. (Stuttg.) 13: 35 1965;
• 11 Honour A. J, Mitchell J. R. A. Platelet clumping in vivo. Nature (Lond.) 197: 1019 1963;
• 12 Honour A. J, Mitchell J. R. A. Platelet clumping in injured vessels. Brit. J. exp. Path 45: 75 1964;
• 13 Mitchell J. R. A, Schwartz C. J. Arterial Disease, pp 201 and 331. Blackwell; Oxford: 1965
• 14 Mitchell J. R. A, Sharp A. A. Platelet clumping in vitro. Brit. J. Haemat 10: 78 1964;
• 15 O’Brien J. R. A comparison of platelet aggregation produced by seven compounds and a comparison of their inhibitors. J. clin. Path 17: 275 1964;
• 16 Øllgaard E. Macroscopic studies of platelet aggregation. Nature of an aggregating factor in red blood cells and platelets. Thrombos. Diathes. haemorrh. (Stuttg.) 6: 86 1961;
• 17 Robinson Jr. G. W, Mason R. G, Wagner R. H. Effect of sulfhydryl inhibitors on platelet agglutinability. Proc. Soc. exp. Biol. (N. Y.) 113: 857 1963;
• 18 Spriggs A. I, Alexander R. F. An albumin gradient method for separating the different white cells of blood, applied to the concentration of circulating tumour cells. Nature (Lond.) 188: 863 1960;
• 19 Welch W. H. The structure of white thrombi. Trans. Path. Soc. Philadelphia 13: 281 1887;