Figure 3

IRF8-deficient microglia in the mixed glial cultures exhibited a hyperproliferative phenotype in response to M-CSF and GM-CSF. A-I, Phase contrast images of mixed glial cultures from Irf8 ^+/+ (A-C), Irf8 ^+/- (D-F), and Irf8 ^-/- (G-I) brain tissues. Cells were transferred to medium alone (control), medium supplemented with M-CSF (20 ng/ml) or GM-CSF (20 ng/ml) at 5 days in vitro, and then maintained in the same medium for another 4 days. Most microglia were seen as phase-bright round cells on the sheet of flat glial cells. Scale Bar: 50 μm. (J-K) Percentages of EdU-positive cells in total CD11b⁺ (J) or CD11b^- (K) cells in the mixed glial cultures of the respective genotypes. Cells treated medium alone (cont), or medium supplemented with M-CSF (20 ng/ml) or GM-CSF (20 ng/ml) for 4 days were exposed to EdU at 6 hours prior to fixation, and double-stained for CD11b and EdU. **P < 0.01 and N.S indicates no significant difference in a comparison of the two groups indicated.