Platelet-leukocyte mixed conjugates in patients with atrial fibrillation.
Although platelets may contribute to the inflammatory component in atrial fibrillation (AF), the impact of platelet-leukocyte mixed conjugates has not yet been determined. Seventeen patients with persistent AF (8/9 m/f; mean age 68.1 +/- 2.5 years), not on anticoagulant therapy, were recruited and compared to 34 healthy controls with normal sinus rhythm (16/18 m/f; mean age 60.8 +/- 1.2 years). Platelet-leukocyte mixed conjugates, platelet P-selectin and leukocyte activation markers (CD11b, myeloperoxidase) were measured by flow-cytometry in whole blood both in basal condition and after in vitro ADP/collagen challenge. Plasma D-dimer and soluble P-selectin were also measured. Statistical analyses were performed by Mann-Whitney or Wilcoxon U test for intergroup differences. In AF patients platelet count, as well as platelet P-selectin expression and percent platelet-leukocyte conjugates were all significantly lower both in basal condition and upon activation with ADP/collagen. In contrast, both soluble P-selectin and D-dimer were significantly higher than in controls; white blood cell count and leukocyte activation markers were unchanged. In conclusion, the formation of platelet-leukocyte mixed conjugates was unexpectedly reduced in AF, possibly due to less reactive platelets as a consequence of previous in vivo activation by ongoing formation of trace amounts of thrombin.
Alberti
Silvia
S
Laboratory of Cell Biology and Pharmacology of Thrombosis, RE ARTU Research Laboratories, Catholic University, Campobasso, Italy. ccerletti@rm.unicatt.it
Angeloni
Giulia
G
Tamburrelli
Chiara
C
Pampuch
Agnieszka
A
Izzi
Benedetta
B
Messano
Loredana
L
Parisi
Quintino
Q
Santamaria
Matteo
M
Donati
Maria Benedetta
MB
de Gaetano
Giovanni
G
Cerletti
Chiara
C
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000097:blood* / Q000473:pathology; D001792:Blood Platelets / Q000473:pathology*; D016022:Case-Control Studies; D002448:Cell Adhesion; D005260:Female; D006801:Humans; D007249:Inflammation / Q000209:etiology / Q000473:pathology; D007962:Leukocytes / Q000473:pathology* / Q000502:physiology; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D019007:P-Selectin / Q000032:analysis; D015539:Platelet Activation
D019007:P-Selectin