Coagulation and fibrinolytic systems in the acute phase response. The biological systems activated during the acute phase response rapidly change and can be generally divided into 2 biologically distinct phases: “contain” and “remodel/repair.” Following injury, exposure of activating cell surfaces and/or matrices activates coagulation and acute inflammation, which work together and lead to thrombin activation and conversion of fibrinogen to fibrin. Together, acute inflammation, thrombin activity, and fibrin serve to contain ruptured compartments (eg, bleeding) and prevent or mitigate invasion by pathogens. Once containment is achieved, the acute phase response transitions to remodel/repair (circular arrows). Importantly, although inflammatory cells are crucial in both phases of the acute phase response, their phenotype and biological role is different in their respective phases. Plasmin promotes remodeling/repair because it is used by reparative inflammatory cells to degrade and remove damaged tissues and fibrin to promote angiogenesis and tissue differentiation/reconstruction. Collectively, in cases of a normal reparative response to injury, coagulation and fibrinolytic components work in concert to promote the transition of inflammatory cells to a reparative (tissue remodeling) phenotype as well as other mechanisms, culminating in timely tissue regeneration.