Fig 1: Characterization of macrophage phenotypes in rats at different ages. (A) Expression levels of M1 and M2 markers in the neonatal, adult and aged lung tissues. iNOS and CD86 are markers for M1; Arg-1 and CD206 are markers for M2. *P<0.05 vs. adults (Kruskal-Wallis; n=5). (B) Upper quadrants of flow cytometry diagrams represent the amount of circulating blood cells that co-expressed the M1 marker CD86 (x-axis) and monocyte marker CD68 (y-axis). Representative histograms for isotype controls for CD86 and CD68 staining in total white blood cells (lower left panel). The percentage of CD86+/CD68+ cells in the peripheral blood was significantly higher in neonates than adults. *P=0.007 vs. neonates, assessed using an independent t-test (adult, n=3; neonate, n=9). iNOS, inducible nitric oxide synthase; Arg, arginase.