title: Patients with venous stasis ulceration have increased monocyte-platelet aggregation.
abstract: OBJECTIVE
  Leukocyte activation has been implicated in the pathogenesis of venous stasis ulceration, but the involvement of activated platelets and leukocyte-platelet aggregates has not been previously investigated. The purpose of this study was to determine whether patients with venous stasis ulceration have increased platelet activation and a propensity toward formation of leukocyte-platelet aggregates.
  
  
  METHODS
  Blood was drawn from the superficial veins of the leg just proximal to a venous stasis ulcer and from an antecubital vein in 14 patients with venous stasis ulceration. Blood was also drawn from the antecubital vein of 14 volunteers without evidence of venous disease. Whole-blood flow cytometry was used to analyze the samples before and after activation with a panel of agonists for evidence of platelet activation and the formation of leukocyte-platelet aggregates.
  
  
  RESULTS
  Patients with venous stasis ulceration had a greater number of monocyte-platelet aggregates in both the arm and leg samples than did the control subjects (p < 0.01). Furthermore, antecubital blood samples from patients with venous stasis ulceration stimulated with either thrombin-receptor agonist peptide, adenosine diphosphate, or phorbol myristate acetate formed more monocyte-platelet aggregates than did control samples (p < 0.05). No differences in platelet activation or neutrophil-platelet aggregate formation were noted among the three sample groups.
  
  
  CONCLUSIONS
  Patients with venous stasis ulceration have an increase in the number of monocyte-platelet aggregates in systemic venous blood as well as in venous blood adjacent to a venous stasis ulcer, implicating the monocyte as the leukocyte involved in the pathogenesis of venous stasis ulceration. No association was identified between the presence of a venous stasis ulcer and either neutrophil-platelet aggregation or the activation of individual platelets. Because platelet activation is necessary for the formation of monocyte-platelet aggregates, these data also suggest that monocyte-platelet aggregation is a more sensitive marker for in vivo platelet activation than is the identification of individual activated platelets.
authors.affiliation: Department of Surgery, Center for Platelet Function Studies, University of Massachusetts Medical Center, Worcester 01655, USA.
authors.forename: B D
authors.initials: BD
authors.lastname: Peyton
authors.forename: M J
authors.initials: MJ
authors.lastname: Rohrer
authors.forename: M I
authors.initials: MI
authors.lastname: Furman
authors.forename: M R
authors.initials: MR
authors.lastname: Barnard
authors.forename: L J
authors.initials: LJ
authors.lastname: Rodino
authors.forename: S E
authors.initials: SE
authors.lastname: Benoit
authors.forename: H B
authors.initials: HB
authors.lastname: Hechtman
authors.forename: C R
authors.initials: CR
authors.lastname: Valeri
authors.forename: A D
authors.initials: AD
authors.lastname: Michelson
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D000911:Antibodies, Monoclonal; D002449:Cell Aggregation / Q000187:drug effects; D002908:Chronic Disease; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000187:drug effects; D010446:Peptide Fragments / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects; D013268:Stimulation, Chemical; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014647:Varicose Ulcer / Q000097:blood*
chemical_list: D000911:Antibodies, Monoclonal; D010446:Peptide Fragments; C076901:thrombin receptor-activating peptide (P508-530); D000244:Adenosine Diphosphate; D013755:Tetradecanoylphorbol Acetate