Cardiopulmonary bypass leads to a preferential loss of activated platelets. A flow cytometric assay of platelet surface antigens.
OBJECTIVE
In a prospective study surface antigens associated with platelet activation, aggregation, and adhesion and the platelet volume were measured to investigate the mechanism of the platelet function defect of cardiopulmonary bypass (CPB).


METHODS
Blood samples were obtained during cardiac surgery before and after heparinization, as well as during and following extracorporeal circulation. The expression of the platelet surface glycoproteins (GP) IIb-IIIa, Ib, 53, and the granule membrane protein (GMP) 140 were measured using flow cytometry in platelet-rich plasma (PRP) before and after in vitro stimulation with adenosine diphosphate. A full blood count including mean platelet volume (MPV) was taken.


RESULTS
Heparinization resulted in a significant increase of GP 53 and GMP 140 and a significant decrease of GP Ib expression. During and following CPB, GP IIb-IIIa and Ib were significantly decreased. Similarly, the expression of the activation markers was reduced significantly. The mean platelet volume decreased significantly from 8.6 +/- 0.7 fl at baseline to 7.9 +/- 0.8 fl at the end of the study period.


CONCLUSIONS
Our data suggest that heparinization induces platelet activation. We assume that a loss of larger and more activated platelets from the circulation contributes substantially to the platelet function defect of CPB.
Department of Cardiae, Thoracic and Vascular Surgery, Klinikum Regensburg, University of Regensburg, Germany.
A
A
Wahba
G
G
Black
M
M
Koksch
G
G
Rothe
J
J
Preuner
G
G
Schmitz
D E
DE
Birnbaum
D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects*; D015703:Antigens, CD / Q000378:metabolism*; D001791:Blood Platelet Disorders / Q000209:etiology* / Q000276:immunology / Q000378:metabolism; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D005434:Flow Cytometry; D006023:Glycoproteins / Q000378:metabolism*; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D008875:Middle Aged; D015539:Platelet Activation; D010979:Platelet Function Tests; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism*; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000378:metabolism*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D011446:Prospective Studies; D060149:Tetraspanin 30
D000925:Anticoagulants; D015703:Antigens, CD; C554586:CD63 protein, human; C033904:GP 140; D006023:Glycoproteins; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019038:Platelet Glycoprotein GPIb-IX Complex; D010980:Platelet Membrane Glycoproteins; D060149:Tetraspanin 30; D006493:Heparin