P-selectin expression, but not GPIIb/IIIa activation, is enhanced in the inflammatory stage of Takayasu's arteritis.

BACKGROUND: Inflammation and thrombosis are closely related processes, but the association between disease activity and thrombogenicity in Takayasu's arteritis (TA) is poorly understood. To investigate the link between platelet activation and disease activity, flow cytometric analyses of platelet P-selectin and activated GPIIb/IIIa expression were performed in patients with TA. METHODS AND
RESULTS: Twenty-two patients with TA, classified into active (Group A, n = 9) and inactive (Group I, n = 13) according to blood-derived inflammatory markers, and 14 healthy age- and gender-matched controls (Group C) were studied. Compared with Group C, the mean fluorescence intensity of P-selectin in response to 0.1-10 micromol/L of ADP was significantly upregulated in Group A, but not in Group I. No differences in platelet GPIIb/IIIa expression in stimulated platelets were seen among the 3 groups. Standard platelet aggregation studies revealed that disease activity did not influence platelet aggregation by ADP.
CONCLUSIONS: P-selectin expression, but not activated GPIIb/IIIa, is enhanced in ADP-activated platelets from patients in the inflammatory stage of TA. P-selectin may play a significant role in the inflammatory and thrombotic responses associated with intractable TA, presumably by inducing platelet-leukocyte interactions.