Thromb Haemost 1994; 72(05): 750-756
DOI: 10.1055/s-0038-1648953
Original Article
Schattauer GmbH Stuttgart

Neutrophil but not Monocyte Activation Inhibits P-Selectin-Mediated Platelet Adhesion[*]

Authors

  • Henry M Rinder

    The Departments of Laboratory Medicine and Anesthesiology, Yale University School of Medicine, New Haven, CT, USA
  • Jayne L Tracey

    The Departments of Laboratory Medicine and Anesthesiology, Yale University School of Medicine, New Haven, CT, USA
  • Christine S Rinder

    The Departments of Laboratory Medicine and Anesthesiology, Yale University School of Medicine, New Haven, CT, USA
  • David Leitenberg

    The Departments of Laboratory Medicine and Anesthesiology, Yale University School of Medicine, New Haven, CT, USA
  • Brian R Smith

    The Departments of Laboratory Medicine and Anesthesiology, Yale University School of Medicine, New Haven, CT, USA
Weitere Informationen

Publikationsverlauf

Received 04. März 1994

Accepted after resubmission 28. Juli 1994

Publikationsdatum:
26. Juli 2018 (online)

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Summary

Selectins are Ca2+-dependent glycoprotein receptors that mediate the adhesion of activated platelets or endothelial cells to unstimulated leukocytes. Using purified cell fractions, we examined activated neutrophil adhesion to P-selectin-expressing platelets and found that phorbol 12-myristate 13-acetate (PMA), platelet activating factor C16 (PAF), and n-formyl-met-leu-phe (fMLP) pretreatment of neutrophils inhibited activated platelet adhesion. Furthermore, PMA and PAF were capable of dissociating established resting neutrophil-activated platelet conjugates. Since L-selectin is downregulated after leukocyte activation and has been postulated as a ligand for P-selectin, we preincubated resting neutrophils with Dreg-2 and Dreg-56, blocking monoclonal antibodies (MoAb) to L-selectin; these MoAb failed to inhibit activated platelet adhesion. To more closely approximate in vivo conditions of leukocyte and platelet activation, we also employed a whole blood (WB) model of leukocyte-platelet adhesion. We found that simultaneous activation of both platelets and leukocytes by PMA caused an immediate rise in the % of P-selectin-positive platelets accompanied by a rapid increase in monocyte-platelet and neutrophil-platelet conjugates; however, the % of neutrophil-platelet conjugates subsequently declined over 30-60 min to baseline levels while monocyte-platelet adhesion remained elevated over 90 min. By contrast, selective platelet activation in WB by thrombin resulted in an increase in platelet P-selectin expression accompanied by a sustained (90 min) elevation in both monocyte- and neutrophil-platelet conjugates. This increase in leukocyte-platelet conjugates after thrombin was not inhibited by preincubation of WB with Dreg-2 or Dreg-56. We conclude that neutrophil activation decreases the expression of the ligand for platelet P-selectin within 30-60 min resulting in inhibition of neutrophil-platelet adhesion and dissociation of existing neutrophil-platelet conjugates. By contrast, monocyte activation over 90 min does not affect monocyte adhesion to activated platelets in whole blood.

* Supported by grants HL02668 (HMR) and HL47193 (BRS) from the National Institutes of Health and the Donaghue Foundation (DL). CSR is a Clinician-Scientist of the American Heart Association., BRS is a Scholar of the Leukemia Society of America.