Characterization of the myeloid cells recruited to the tumor cells. (A) Cx₃cr1^gfp/+ mice were intravenously injected with 5 × 10⁵ CMRA-stained B16F10-wt cells (blue). At 8 hours, lungs were isolated and analyzed by immunohistochemistry. Representative images, acquired with a confocal microscope, from a double staining for CD11b (red, ELF97) and CD11c (red, APC) are shown. The percentage of CX₃CR1-GFP cells within a cluster that coexpressed CD11b, CD11c, or both markers was analyzed; n = 3 mice; ≥ 10 clusters per mouse analyzed (1-way ANOVA and Tukey test). White boxes define areas enlarged in panels below. (B) Representative images, acquired with a confocal microscope, of sections from panel A stained for the presence of F4/80, CD68, Gr-1, CD3ϵ, and CD45 (all red, AlexaFluor-633) and the percentage of CX₃CR1-GFP cells within the clusters that coexpressed these markers; n = 3 mice; ≥ 10 clusters per mouse analyzed for each marker (1-way ANOVA and Tukey test). (A-B) Data are mean + SD. *P < .05. ***P < .001. Scale bars represent 50 μm.