This Article Order Full text via Infotrieve Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Peerschke, E. I. Search for Related Content PubMed PubMed Citation Articles by Peerschke, E. I.

American Journal of Pathology, Vol 147, 678-687, Copyright © 1995 by American Society for Investigative Pathology

REGULAR ARTICLES

Bound fibrinogen distribution on stimulated platelets. Examination by confocal scanning laser microscopy

EI Peerschke
Department of Pathology, State University of New York at Stony Brook 11794-7300, USA.

Previous studies have suggested that qualitative changes in platelet bound fibrinogen modulate platelet aggregation. The present study used confocal scanning laser microscopy to further evaluate post-ligand binding events over a 60-minute time course. When fluorescein isothiocyanate (FITC)-streptavidin was added to ADP-stimulated platelets 1 minute after biotinylated fibrinogen binding at 22 degrees C, bound fibrinogen was found in variously sized patches on the cell surface. When streptavidin was added 60 minutes later, bound fibrinogen had been cleared from the platelet surface and was observed in clusters penetrating into platelets to various extents. ADP-activated platelets did not stain with a monoclonal antibody against CD62 suggesting that platelets were not permeabilized during the experiment and had not released alpha-granules. Additional studies using either biotinylated fibrinogen that had been prelabeled with FITC-streptavidin or FITC- labeled fibrinogen revealed similar patterns of platelet-associated fibrinogen clearance and redistribution. Pretreatment of platelets with cytochalasin D prevented this redistribution. Dual labeling experiments using biotinylated fibrinogen and FITC-streptavidin as well as a monoclonal anti-GPIIIa antibody labeled with rhodamine-conjugated anti- mouse IgG demonstrated the co-localization of fibrinogen and GPIIIa. Similar observations were made with fibrinogen bound to thrombin- stimulated platelets. In contrast, fibronectin bound to thrombin- activated platelets retained a predominantly surface membrane distribution under identical experimental conditions. Since surface- cleared fibrinogen was accessible to exogenous FITC-streptavidin under conditions that did not lead to platelet permeabilization, the data suggest fibrinogen deposition in compartments that are accessible to the extracellular milieu. This is consistent with the ability of exogenous plasmin to completely remove cleared fibrinogen pools without detectable fibrinogen reexpression on the platelet surface or alpha- granule secretion. The data provide morphological evidence for the selective, GPIIb-IIIa mediated, actin-dependent clearance of bound fibrinogen from the activated platelet surface, suggesting a mechanism for preventing and limiting thrombus development.

This article has been cited by other articles:

				T. Hato, N. Pampori, and S. J. Shattil Complementary Roles for Receptor Clustering and Conformational Change in the Adhesive and Signaling Functions of Integrin alpha IIbbeta 3 J. Cell Biol., June 29, 1998; 141(7): 1685 - 1695. [Abstract] [Full Text] [PDF]

				S. J. Shattil, H. Kashiwagi, and N. Pampori Integrin Signaling: The Platelet Paradigm Blood, April 15, 1998; 91(8): 2645 - 2657. [Full Text] [PDF]

				H. Kashiwagi, M. A. Schwartz, M. Eigenthaler, K.A. Davis, M. H. Ginsberg, and S. J. Shattil Affinity Modulation of Platelet Integrin alpha IIbbeta 3 by beta 3-Endonexin, a Selective Binding Partner of the beta 3 Integrin Cytoplasmic Tail J. Cell Biol., June 16, 1997; 137(6): 1433 - 1443. [Abstract] [Full Text] [PDF]