Increased plasma levels of soluble CD40 ligand correlate with platelet activation markers and underline the need for standardized pre-analytical conditions

Abstract

Objectives: To investigate whether sCD40L dosage might represent a useful tool to explore in vivo platelet function.

Design and methods: sCD40L and sP-selectin levels and light transmission aggregometry (LTA) were analyzed in 69 healthy donors. Immunoassays were performed on platelet-depleted citrate plasma samples. The effects of in vitro aspirin treatment on the release of sCD40L were investigated in 15 subjects following platelet stimulation. The effects of a 1-month therapeutic course of low-dose aspirin on sP-selectin and sCD40L levels were also investigated.

Results: A significant correlation was observed between sCD40L and sP-selectin (p<0.01). In vitro aspirin treatment remarkably decreased sCD40L levels following platelet activation by exogenous agonists. sCD40L directly correlated with LTA (Rho=0.62, p<0.0001). In vivo aspirin treatment significantly reduced both sP-selectin and sCD40L levels (both p<0.01) in a direct correlation (Rho=0.66, p<0.05).

Conclusions: Citrated plasma samples reflect sCD40L released from platelets, thus yielding the most valid estimates of in vivo circulating levels of this platelet activation markers.