Correlations of adenosine diphosphate (ADP)-induced platelet aggregation and activation.

<p><b>(A)</b> Scatter plot showing ADP-induced platelet reactivity by light transmission aggregometry (LTA; x-axis) vs. platelet reactivity by the VerifyNow P2Y₁₂ assay (y-axis). Circles represent individual measurements. Cut-off values for high on-treatment residual platelet reactivity are indicated by the dotted lines. PRU, P2Y₁₂ Reaction Units. <b>(B)</b> Scatter plot showing ADP-induced platelet surface P-selectin expression (x-axis) vs. ADP-induced activated glycoprotein (GP) IIb/IIIa (y-axis). Circles represent individual measurements. Cut-off values for high P-selectin and high GPIIb/IIIa are indicated by the dotted lines. <b>(C)</b> Scatter plot showing platelet reactivity by the VerifyNow P2Y₁₂ assay (x-axis) vs. ADP-induced activated glycoprotein (GP) IIb/IIIa (y-axis). Circles represent individual measurements. Cut-off values for high on-treatment residual platelet reactivity and high GPIIb/IIIa are indicated by the dotted lines. PRU, P2Y₁₂ Reaction Units.</p

Correlations of adenosine diphosphate (ADP)-induced platelet reactivity by light transmission aggregometry (LTA), the VerifyNow P2Y₁₂ assay, and multiple electrode aggregometry (MEA) with ADP-induced P-selectin expression and activated glycoprotein (GP) IIb/IIIa.

<p>Correlations of adenosine diphosphate (ADP)-induced platelet reactivity by light transmission aggregometry (LTA), the VerifyNow P2Y₁₂ assay, and multiple electrode aggregometry (MEA) with ADP-induced P-selectin expression and activated glycoprotein (GP) IIb/IIIa.</p

Clinical, laboratory and procedural characteristics of the overall study population.

<p>Continuous data are shown as median (interquartile range). Dichotomous data are shown as n (%).</p><p>ACE inhibitors, angiotensin converting enzyme inhibitors; ARB, angiotensin receptor blockers.</p><p>Clinical, laboratory and procedural characteristics of the overall study population.</p

Correlations of arachidonic acid (AA)-induced platelet aggregation and platelet activation.

<p><b>(A)</b> Scatter plot showing AA-induced platelet reactivity by light transmission aggregometry (LTA; x-axis) vs. platelet reactivity by the VerifyNow aspirin assay (y-axis). Circles represent individual measurements. Cut-off values for high on-treatment residual platelet reactivity are indicated by the dotted lines. ARU, Aspirin Reaction Units. <b>(B)</b> Scatter plot showing AA-induced platelet surface P-selectin expression (x-axis) vs. AA-induced activated glycoprotein (GP) IIb/IIIa (y-axis). Circles represent individual measurements. Cut-off values for high P-selectin and high GPIIb/IIIa are indicated by the dotted lines. <b>(C)</b> Scatter plot showing AA-induced platelet reactivity by light transmission aggregometry (LTA; x-axis) vs. AA-induced activated glycoprotein (GP) IIb/IIIa (y-axis). Circles represent individual measurements. Cut-off values for high on-treatment residual platelet reactivity and high GPIIb/IIIa are indicated by the dotted lines. ARU, Aspirin Reaction Units.</p

Underlying mechanism and specific prevention of hemolysis-induced platelet activation

<p>Thromboembolic complications significantly impair the outcome of hemolytic disorders. We hypothesized that red cell adenosine diphosphate (ADP) release results in significant platelet activation in hemolysis and that this prothrombotic state can be prevented by inhibition of the ADP P2Y₁₂ receptor. In the current study, we therefore sought to investigate the mechanism and inhibition of hemolysis-induced platelet activation. The expression of activated integrin αIIbß3 was determined by flow cytometry, and platelet aggregation was assessed by multiple electrode platelet aggregometry. We demonstrate platelet activation and increased platelet aggregation by adding hemolytic blood (lysates) to whole blood, similarly to that achieved by the platelet agonist ADP. Enhanced platelet activation and reactivity in the presence of hemolytic blood were significantly abolished by apyrase, which catalyzes ADP degradation, and inhibited by blockade of the platelet ADP P2Y₁₂ receptor with cangrelor. Platelets from patients treated with the ADP P2Y₁₂ receptor antagonist clopidogrel showed a reduced response to lysates compared to platelets from healthy controls without antiplatelet treatment. Further, <i>in vitro</i> blood group ABO incompatibility induced hemolysis and led to increased platelet activation. Finally, “spontaneous” platelet aggregation seen in patients with cold agglutinin disease was completely abolished by cangrelor. In conclusion, hemolysis is associated with increased platelet activation and aggregation due to red cell derived ADP, which can be prevented by ADP receptor blockade.</p

Regression coefficients (B), confidence intervals (CI), and p-values (p) of multivariate regression analyses of age, sex, body mass index (BMI), hypertension, hyperlipidemia, diabetes, active smoking, platelet count, white blood cell count (WBC), log transformed interleukin-6 (log IL-6),log transformed high-sensitivity C-reactive protein (log hsCRP), log transformed serum creatinine (log creatinine), and log transformed asymmetric dimethylarginine (log ADMA) for surface expression of P-selectin, activation of glycoprotein (GP) IIb/IIIa, and formation of monocyte-platelet aggregates (MPA).

<p>MFI, mean fluorescence intensity.</p><p>Regression coefficients (B), confidence intervals (CI), and p-values (p) of multivariate regression analyses of age, sex, body mass index (BMI), hypertension, hyperlipidemia, diabetes, active smoking, platelet count, white blood cell count (WBC), log transformed interleukin-6 (log IL-6),log transformed high-sensitivity C-reactive protein (log hsCRP), log transformed serum creatinine (log creatinine), and log transformed asymmetric dimethylarginine (log ADMA) for surface expression of P-selectin, activation of glycoprotein (GP) IIb/IIIa, and formation of monocyte-platelet aggregates (MPA).</p

Clinical and laboratory patient characteristics.

<p>Continuous data are shown as median (interquartile range). Dichotomous data are shown as n (%).</p><p>BMI, body mass index; CRP, C-reactive protein; ACE inhibitors, angiotensin converting enzyme inhibitors; ARB, angiotensin receptor blockers.</p><p>Clinical and laboratory patient characteristics.</p

Regression coefficients (B), confidence intervals (CI), and p-values (p) of multivariate regression analysis of age, sex, body mass index (BMI), hypertension, hyperlipidemia, diabetes, active smoking, platelet count, white blood cell count (WBC), and log transformed serum creatinine (log creatinine) for high interleukin-6 levels (high IL-6) and high asymmetric dimethylarginine (high ADMA).

<p>Regression coefficients (B), confidence intervals (CI), and p-values (p) of multivariate regression analysis of age, sex, body mass index (BMI), hypertension, hyperlipidemia, diabetes, active smoking, platelet count, white blood cell count (WBC), and log transformed serum creatinine (log creatinine) for high interleukin-6 levels (high IL-6) and high asymmetric dimethylarginine (high ADMA).</p

Platelet surface expression of P-selectin and activated glycoprotein (GP) IIb/IIIa.

<p><b>(A)</b> Platelet surface expression of P-selectin in patients with high (>median) vs. low (≤median) interleukin (IL)-6 levels. <b>(B)</b> Platelet surface expression of activated GPIIb/IIIa in patients with high (>median) vs. low (≤median) asymmetric dimethylarginine (ADMA) levels. The boundaries of the box show the lower and upper quartile of data, the line inside the box represents the median. Whiskers are drawn from the edge of the box to the highest and lowest values that are outside the box but within 1.5 times the box length. MFI, mean fluorescence intensity.</p