Effect of aging on cell infiltration. Flow cytometric analysis of brain neutrophils and monocytes in sham or ischemic mice brain 1 and 2 days after ischemia in young and aged mice (A, B). Upper: quantification of total neutrophils and monocytes. Right Lower: quantification of N1 (Ym1−) and N2 (Ym1+) neutrophils (Cd11b+, Ly6Ghi, CD45hi). Left Lower: quantification of M1 (Ym1−) and M2 (Ym1+) monocytes (Cd11b+, CD45hi, CCR2+). Data are mean ± SD, n = 6 to 8 in each group. P < 0.05.