Soluble but not platelet P-selectin correlates with spontaneous platelet aggregation: a pilot study.

Background: P-selectin (PS) is a marker of platelet activation measured on the platelet surface as platelet PS (pPS) or in serum as soluble PS (sPS). Controversy remains over the exact relationship between sPS, pPS, and other markers such as spontaneous platelet aggregation (SPA).

Objective: To investigate correlations between pPS, sPS, and SPA in patients with peripheral arterial disease.

Methods: SPA, pPS, and sPS levels were measured in venous blood sampled from patients following intermittent claudication (n = 18) or an acute stroke (n = 18).

Results: SPA and sPS correlated significantly in the claudicants (Pearson correlation coefficient, r = 0.661; P = .0020) and stroke patients (r = 0.514; P = .020). No significant correlation was identified between pPS and SPA, or sPS and pPS.

Conclusions: The 2 methods of assessing PS are not comparable. Although pPS is accepted as a platelet activation marker, sPS may be a better indicator of aggregation represented by SPA.