In vitro measurement of platelet glycoprotein IIb/IIIa receptor blockade by abciximab: Interindividual variation and increased platelet secretion

F. Rossi, E. Rossi, F. I. Pareti, S. Colli, E. Tremoli, L. Gallo

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Background and Objectives. Inhibition of soluble fibrinogen binding to activated platelets represents the target of pharmacologic approach with antagonists of the glycoprotein IIb/IIIa (GPIIb/IIIa) complex. In this study we assessed the effects of abciximab, a recombinant chimeric Fab fraction of the antibody against GPIIb/IIIa, on several markers of platelet activation. Design and Methods. The platelet surface expression of GPIIb/IIIa was measured by a flow cytometry technique using a two-color assay. GPIIb/IIIa was detected by FITC-conjugated antibodies in whole blood, either unstimulated or exposed to platelet stimuli. The following antibodies were used: CD41, which recognizes the IIb/IIIa complex both in activated and non-activated conformers, and PAC-1, which is directed toward the activated conformer of GPIIb/IIIa. In addition, the same blood sample was incubated with CD62 antibody to measure P-selectin, as a marker of α-granule degranulation. The effect of abciximab was also assessed by experiments carried out on shear stress-induced platelet aggregation, a test that appears to be a predictor of platelet hemostatic function. Results. Abciximab inhibited CD41 binding to glycoprotein IIb (GPIIb) in a concentration-dependent manner and also inhibited the binding of PAC-1 to active GPIIb/IIIa. In contrast, membrane-associated P-selectin was significantly increased by the drug, which suggests that blockade of GPIIb/IIIa receptors results in an increased platelet degranulation in response to agonists. Shear stress-induced platelet aggregation was inhibited by abciximab, with a more pronounced effect on blood filtration, which represents an index of platelet aggregate formation. Interpretation and Conclusions. Our results indicate that GPIIb/IIIa blockade by abciximab is accompanied by an increase of α-granule secretion, suggesting that different mechanisms regulate these aspects of platelet activation. The described flow cytometry technique, that allows the simultaneous in vitro detection of several platelet markers, is a suitable method for assessing the effects of agents which interfere with platelet function.

Original languageEnglish
Pages (from-to)192-198
Number of pages7
JournalHaematologica
Volume86
Issue number2
Publication statusPublished - 2001

Fingerprint

Integrin beta3
Platelet Glycoprotein GPIIb-IIIa Complex
Blood Platelets
P-Selectin
Antibodies
Platelet Activation
Platelet Aggregation
Flow Cytometry
Platelet Membrane Glycoproteins
In Vitro Techniques
abciximab
Fluorescein-5-isothiocyanate
Membrane Glycoproteins
Hemostatics
Fibrinogen
Glycoproteins
Color

Keywords

  • Abciximab
  • Flow cytometry
  • Glycoprotein IIb/IIIa
  • P-selectin
  • Platelets

ASJC Scopus subject areas

  • Hematology

Cite this

In vitro measurement of platelet glycoprotein IIb/IIIa receptor blockade by abciximab : Interindividual variation and increased platelet secretion. / Rossi, F.; Rossi, E.; Pareti, F. I.; Colli, S.; Tremoli, E.; Gallo, L.

In: Haematologica, Vol. 86, No. 2, 2001, p. 192-198.

Research output: Contribution to journalArticle

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T1 - In vitro measurement of platelet glycoprotein IIb/IIIa receptor blockade by abciximab

T2 - Interindividual variation and increased platelet secretion

AU - Rossi, F.

AU - Rossi, E.

AU - Pareti, F. I.

AU - Colli, S.

AU - Tremoli, E.

AU - Gallo, L.

PY - 2001

Y1 - 2001

N2 - Background and Objectives. Inhibition of soluble fibrinogen binding to activated platelets represents the target of pharmacologic approach with antagonists of the glycoprotein IIb/IIIa (GPIIb/IIIa) complex. In this study we assessed the effects of abciximab, a recombinant chimeric Fab fraction of the antibody against GPIIb/IIIa, on several markers of platelet activation. Design and Methods. The platelet surface expression of GPIIb/IIIa was measured by a flow cytometry technique using a two-color assay. GPIIb/IIIa was detected by FITC-conjugated antibodies in whole blood, either unstimulated or exposed to platelet stimuli. The following antibodies were used: CD41, which recognizes the IIb/IIIa complex both in activated and non-activated conformers, and PAC-1, which is directed toward the activated conformer of GPIIb/IIIa. In addition, the same blood sample was incubated with CD62 antibody to measure P-selectin, as a marker of α-granule degranulation. The effect of abciximab was also assessed by experiments carried out on shear stress-induced platelet aggregation, a test that appears to be a predictor of platelet hemostatic function. Results. Abciximab inhibited CD41 binding to glycoprotein IIb (GPIIb) in a concentration-dependent manner and also inhibited the binding of PAC-1 to active GPIIb/IIIa. In contrast, membrane-associated P-selectin was significantly increased by the drug, which suggests that blockade of GPIIb/IIIa receptors results in an increased platelet degranulation in response to agonists. Shear stress-induced platelet aggregation was inhibited by abciximab, with a more pronounced effect on blood filtration, which represents an index of platelet aggregate formation. Interpretation and Conclusions. Our results indicate that GPIIb/IIIa blockade by abciximab is accompanied by an increase of α-granule secretion, suggesting that different mechanisms regulate these aspects of platelet activation. The described flow cytometry technique, that allows the simultaneous in vitro detection of several platelet markers, is a suitable method for assessing the effects of agents which interfere with platelet function.

AB - Background and Objectives. Inhibition of soluble fibrinogen binding to activated platelets represents the target of pharmacologic approach with antagonists of the glycoprotein IIb/IIIa (GPIIb/IIIa) complex. In this study we assessed the effects of abciximab, a recombinant chimeric Fab fraction of the antibody against GPIIb/IIIa, on several markers of platelet activation. Design and Methods. The platelet surface expression of GPIIb/IIIa was measured by a flow cytometry technique using a two-color assay. GPIIb/IIIa was detected by FITC-conjugated antibodies in whole blood, either unstimulated or exposed to platelet stimuli. The following antibodies were used: CD41, which recognizes the IIb/IIIa complex both in activated and non-activated conformers, and PAC-1, which is directed toward the activated conformer of GPIIb/IIIa. In addition, the same blood sample was incubated with CD62 antibody to measure P-selectin, as a marker of α-granule degranulation. The effect of abciximab was also assessed by experiments carried out on shear stress-induced platelet aggregation, a test that appears to be a predictor of platelet hemostatic function. Results. Abciximab inhibited CD41 binding to glycoprotein IIb (GPIIb) in a concentration-dependent manner and also inhibited the binding of PAC-1 to active GPIIb/IIIa. In contrast, membrane-associated P-selectin was significantly increased by the drug, which suggests that blockade of GPIIb/IIIa receptors results in an increased platelet degranulation in response to agonists. Shear stress-induced platelet aggregation was inhibited by abciximab, with a more pronounced effect on blood filtration, which represents an index of platelet aggregate formation. Interpretation and Conclusions. Our results indicate that GPIIb/IIIa blockade by abciximab is accompanied by an increase of α-granule secretion, suggesting that different mechanisms regulate these aspects of platelet activation. The described flow cytometry technique, that allows the simultaneous in vitro detection of several platelet markers, is a suitable method for assessing the effects of agents which interfere with platelet function.

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