A 5-year-old boy punctures his thumb with a rusty nail. Four hours later, the thumb appears red and swollen. Which of the following serum proteins activates the complement, coagulation, and fibrinolytic systems at the site of injury in the patient?

Hageman factor. Hageman factor (clotting factor XII) provides a key source of vasoactive mediators. Activation of this plasma protein at the site of tissue injury stimulates (1) conversion of plasminogen to plasmin, which induces fibrinolysis; (2) conversion of prekallikrein to kallikrein, which generates vasoactive peptides of low molecular weight referred to as kinins; (3) activation of the alternative complement pathway; and (4) activation of the coagulation system. Although the other choices are mediators of inflammation, they have a more restricted set of functions.Diagnosis: Inflammation