Circulating platelet/polymorphonuclear leukocyte mixed-cell aggregates in patients with mechanical heart valve replacement

There is convincing evidence that cell adhesion plays an important role in cardiovascular pathology and is frequently associated to "in vivo" cellular activation. This study involves patients with mechanical heart valve repla cement (MHVR patients) who have increased platelet polymorphonuclear leukoc yte (PMN) reactivity, Dual-color cytometry was used to determine the expres sion of adhesive molecules on cellular surfaces, platelet, and PMN-bound fi brinogen as well as the presence of circulating platelet/PMN mixed-cell agg regates (MCA) in 55 MHVR patients, 49 control patients under oral anticoagu lant therapy, and 22 healthy volunteers, The results demonstrated that (a) PMN from MHVR patients showed an increased PMN-bound fibrinogen (mean +/- S EM: 1,420 +/- 169 antifibrinogen fluorescence intensity, P = 0.0012), when compared to controls (mean +/- SEM: 747 +/- 32 anti-fibrinogen fluorescence intensity) and healthy volunteers (mean +/- SEM: 692 +/- 25 anti-fibrinoge n fluorescence intensity; Ib) platelet activation in MHVR patients was evid enced by the higher expression of CD62P (mean +/- SEM: 128 +/- 19 anti- CD6 2P fluorescence intensity, P = 0.003) compared to controls (mean +/- SEM: 6 5 +/- 15 and 50 +/- 10 anti CD62P fluorescence intensity) and by increased levels of platelet-bound fibrinogen (mean +/- SEM: 625 +/- 20 anti-fibrinog en fluorescence intensity, P = 0.0043 versus 496 +/- 45 and 480 +/- 30 for control patients and for healthy volunteers, respectively); and (c) the pro portion of MCA in MHVR patients (15 +/- 2%) was significantly higher (P = 0 .009) compared to controls (7 + 1%) and healthy volunteers (6 +/- 2%). The results indicate that the presence of stable circulating MCA represents ano ther marker of "in vivo" PMN activation in MHVR patients. (C) 2000 Wiley-Li ss, Inc.