IFNβ alleviates neuroinflammation in delayed tPA–treated ischemic stroke. Mice were subjected to 3-hour MCAO followed by IV administration of vehicle, tPA, or tPA plus IFNβ. (A) At 13 hours postinjury, mononuclear cells were isolated from the ischemic brain of vehicle-, tPA-, and tPA plus IFNβ-treated MCAO mice (n = 6-7 per group), and the isolated cells were then stained with antibodies of CD45, CD11b, CD80, and CD86 followed by FACS analysis. MG were determined based on their expression of CD45^intCD11b⁺, and MG with positive expression of CD80 and CD86 were then determined. Isotype controls (ISO) were used as a negative control to determine positive expression of CD80 or CD86. (B) At 20 hours postinjury, the brain tissues harvested from vehicle-, tPA-, and tPA plus IFNβ-treated MCAO mice were subjected to immunohistochemistry (IHC), and Iba1⁺ cells in the ipsilateral cortex and striatum of periinfarct regions were quantified (n = 6 per group). Scale bars, 50 µm. (C) The brain tissues were also subjected to quantitative polymerase chain reaction (Q-PCR) analysis for IL-1α, IL-1β, TNFα, CCL3, MMP3, and MMP9 messenger RNA expression (n = 5-8 per group). *P < .05 by 1-way ANOVA, **P < .01 by Kruskal-Wallis test (B) or 1-way ANOVA (C).