Figure 3.

Intraspinal accumulation of monocyte-derived macrophages is increased in CX3CR1^GFP/GFP mice. All CNS macrophages (microglia+MDMs) were identified by gating on CD11b⁺ events identified in forward versus side scatter plots (FSC vs SSC, respectively). A, Representative contour plots (outliers removed for clarity) show CD11b⁺ populations in wild-type and CX3CR1^GFP/GFP mice as a function of time after injury [0 (naive), 1, 3, 7, and 14 dpi]. Horizontal lines indicate positive expression defined with isotype controls. B, Quantification of plots in A reveal that the CNS macrophage response is modestly increased in CX3CR1^GFP/GFP mice, especially at later times after injury when MDMs are expected to infiltrate the spinal cord (significant main effect of time, p < 0.0001 and genotype, p = 0.0286). C, Representative histograms show CD45 high (MDMs) and low (microglia) populations from naive and SCI wild-type and CX3CR1^GFP/GFP. Relative expression of CD45 was analyzed from the CD11b⁺ gate (one example is shown). Vertical dotted lines indicate distinction between CD45 high and low expression. D, Entry of CD45^hi MDMs is maximal at 3 dpi and is greater in CX3CR1^GFP/GFP mice (significant effect of time, p < 0.0001, and genotype, *p = 0.0017). Data were analyzed by two-way ANOVA followed by Bonferroni's post hoc test. n = 3–4 mice/genotype/time.