Coagulation factors can activate leukocytes. (A) Thrombin and APC cleave PAR-1 expressed on monocytes, and regulate monocyte proinflammatory and procoagulant properties. (B) Coagulation factors and activated platelets interact with neutrophils to regulate neutrophil degranulation, NET release, and phagocytic and chemotactic activities. APC, activated protein C; PAMP, pathogen-associated molecular pattern.