RNase treatment reduces leukocyte infiltration and mast cell degranulation. (A-D,F-H) Quantitative analyses, using flow cytometry, of infiltrated leukocytes in adductor muscles isolated at day 1 or 3 after induction of arteriogenesis via FAL. Scatter plots show the percentages of CD45⁺ cells (A,C,F), CD45⁺/Gr1⁺/CD115⁻ cells (B,D,G), and CD45⁺/F4/80⁺ cells (H) in adductor muscles from mice treated with saline or RNase A (A-B,F-H) or from mice treated with saline, recombinant inactive human RNase1, or recombinant active human RNase1 (C-D). Analyses were performed at day 1 (A-D) and day 3 (F-H) after FAL. (E) The scatter plot shows the number of degranulated mast cells in the perivascular space of growing collaterals at day 3 after induction of arteriogenesis in mice treated with saline, RNase A, recombinant active or inactive human RNase1, or the mast cell stabilizer cromolyn, as evaluated on Giemsa-stained tissue sections. Counts of white blood cell (WBC) populations in blood samples drawn from mice at day 1 (I) or day 3 (J) after induction of arteriogenesis by FAL and saline or RNase A treatment. Data are mean ± SEM. n = 6 mice per group (A-D,F-J), n > 10 mice per group (E). The dashed horizontal line in the scatter plots indicates the mean sham value. *P < .05, unpaired Student t test (A-B,F-J), 1-way ANOVA with the Bonferroni multiple-comparison test (C-E). Lymph, lymphocytes; Mono, monocytes; Neut, neutrophils.