Optical Density Variations and Microscopic Observations in the Evaluation of Platelet Shape Change and Microaggregate Formation

Summary

Addition of Ristocetin to formalin-fixed platelets suspended in diluted PPP induces a marked increase in turbidity which is not caused by platelet shape change but by the formation of microaggregates. If diluted PPP of patients with severe von Willebrand's disease is used, only an initial increase in turbidity and no further decrease is observed without any form variation of the platelets but again with formation of many microaggregates. In normal PRP diluted with buffered EDTA, ADP induces an increase in turbidity without further changes in optical density. Simultaneously platelets immediately change their shape with formation of pseudopodes and sphering but at the same time also microaggregates appear. Shape change and microaggregate formation can also be observed after the addition of Collagen to undiluted PRP which is followed by the formation of large aggregates and a decrease in optical density. Increase in optical density in undiluted PRP is not a specific indicator of platelet shape changes. Microaggregates can alone or partially be responsible for these changes. For the evaluation of platelet shape changes but also for the estimation of microaggregate formation microscopic methods are preferred.

Key words

Platelet shape change - Aggregation - Microaggregate formation - Formalin-fixed platelets - Optical density

• References

• 1 Wiedemann R, Breddin K. Morphologische Veränderungen von Thrombozyten nach der Blutentnahme und während der Thrombusbildung. Med. Welt 1978; 29: 1146-1148
• 2 Born GV R. Observations on the change in shape of blood platelets brought about by adenosine-diphosphate. J physiol 1970; 209: 487-511
• 3 Lloyd JV, Nishizawa EE, Mustard JF. Effect of ADP-induced shape change of incorporation of 32^p into platelet phosphatidic acid and mono-di-triphosphatidyl inositol. Brit J Haematol 1973; 25: 77-99
• 4 Patscheke H, Wörner P, Brossmer R. The relationship between shape change and release reaction of lecitin stimulated platelets. Effects of cytochalasine B and prostaglandin E₁ . Thromb Res 1997; 10: 465-474
• 5 Patscheke H, Wörner P. Platelet activation detected by turbido metric shape change analysis. Differential influence of cytochalasine B and prostaglandin E₁ . Thromb Res 1978; 12: 485-496
• 6 Kinlough-Rathbone RL, Packham MA, Reimers HJ, Cazenave JP, Mustard JF. Mechanism of platelet shape change, aggregation and release induced by collagen, thrombin or 23, 187. J Lab clin med 1979; 90: 707-719
• 7 Frojmovic MM. Rheoptical studies of platelet structure and function. In: Spaet TH. (Ed) Progr Haemostas Thromb 4. Grune & Stratton: 1978: 279-319
• 8 Blasberg PL, Wurzinger J. Platelet aggregometry and shape change by laser light in small samples. VII Int Cong Thromb Haemostas 1979 Abstr 314
• 9 Breddin K, Grun H, Ziemen M, Bauer O, Krzywanek HJ. Factors influencing spontaneous and induced platelet aggregation. Studies with a new aggregometer. In: Platelets, recent advances in basic research and clinical aspects.. Excerpta Medica Int Congress Series: 1975. 357 302-314
• 10 Pietsch U, Lippmann M, Scharrer I, Breddin K. Neue Befunde zur Wirkung von Acetylsalizylsäure. Die Hemmwirkung auf den Formwandel der Thrombozyten und ihre Bedeutung für die Dosierung als Antithrombotikum. In: Alexander K, Cachovan M. Diabetische Angiopathien. G Witzstrock, Baden-Baden, New York: 1977: 348-351
• 11 Bamberg E, Bauer O, Hermann W, Kroemer H, Lippmann M, Müller Ch, Stegmann H, Breddin K. Primärer Formwandel der Thrombozyten in vitro. Blut 1978; 37: 327-339
• 12 Breddin K, Grun H, Krzywanek HJ, Schremmer WP. On the measurement of spontaneous platelet aggregation. The platelet aggregation test III. Methods and first clinical results. Thromb Haemostas Stuttg 1976; 35: 669-691