IFN-α treatment is prothrombotic in old mice subjected to stroke. Mice were treated for 3 days with either vehicle or IFN-α. Twenty-four hours after the induction of transient middle cerebral artery occlusion in young (age, 4-6 months) and old (age >24 months) mice, brain tissue and plasma were collected. (A) Quantification of neutrophil recruitment in all groups in the ipsilesional hemisphere, that is, where the ischemic injury occurred. (B) Plasma CRP levels and (C) plasma IL-6 levels were determined by ELISA. (D) Brain tissue was stained for platelets, and platelet deposition in ipsilesional brain tissue from young and old mice was quantified. (E) Brain tissue was stained for fibrin(ogen), and fibrin(ogen) deposition in ipsilesional brain tissue from young and old mice was quantified. (F) Plasma VWF levels and (G) plasma TAT levels were determined by ELISA. All data are represented as mean ± standard deviation. ELISA, enzyme-linked immunosorbent assay.