Background Inorganic polyphosphates (polyP), which are secreted by activated platelets
(short‐chain polyP) and accumulate in some bacteria (long‐chain polyP), support the
contact activation of factor XII (FXII) and accelerate the activation of FXI. Objectives The aim
of the present study was to evaluate the role of FXI in polyP‐mediated coagulation activation
and experimental thrombus formation. Methods and Results Pretreatment of plasma with
antibodies that selectively inhibit FXI activation by activated FXII (FXIIa) or FIX) activation by …