Saliva triggers coagulation activation of whole blood. (A) Blood was incubated without (dotted line) or with (solid line) cell-free autologous saliva. Clot formation was initiated by addition of calcium chloride (t = 0) and monitored by thromboelastography for 1 hour. (B) Summary of clotting times from blood incubated without saliva, with cell-free saliva in the absence or presence of antifactor VII or antifactor XII, or with vesicle-depleted saliva (supernatant; n = 10). (C) Human wound blood was incubated without or with cell-free saliva, both in the absence or presence of antifactor VII (n = 5). (D) Blood was incubated with cell-free saliva or reptilase, snake venom, which directly converts fibrinogen into insoluble fibrin.