Expression of CD154 and subsequent sCD154 release occur in the physiologic blood-clotting reaction.

Whole blood collected in EDTA, or cellular blood components obtained from the same blood samples and adjusted in autologous plasma to physiologic concentrations, were subjected to the clotting reaction by addition of 20 mM calcium (■) or 0.2 U/mL human thrombin (▩) for 1 hour at 37°C. sCD154 concentrations were determined in cell-free supernatants by ELISA. ■, unstimulated. Experiments were performed in triplicate; data are shown as mean ± SD and are representative of 3 independent experiments.