Time course of inflammatory macrophage– and anti-inflammatory macrophage–associated gene expression in the brain after traumatic brain injury. Changes in RNA expression of inflammatory macrophage (M1) and anti-inflammatory macrophage (M2) macrophagic and microglial markers peaked in ipsilateral brain tissue at 5 days postinjury (DPI) as assessed by quantitative RT-PCR. Statistically significant fold changes at 5 DPI relative to control and contralateral sides occurred for CD68, CD86, ionized calcium-binding adapter molecule 1 (Iba1) and mannose receptor, C type 1 (Mrc1). Changes in CD80 were significant when ipsilateral sides were compared to contralateral sides, but not in controls. In contrast, expression of tumor necrosis factor α (Tnf) was highest at 24 hours and 3 DPI, but there were no statistically significant fold changes in RNA expression of arginase 1 (Arg1), CD80, CD163 or nitric oxide synthase 2 (Nos2). Error bars indicate standard errors of the mean. *P < 0.05.