Figure 7

Neutrophils are recruited to early lesions and are maintained at the margin of liver metastases over time. Paraffin-embedded sections from liver metastases were collected at early (1.5 week) or late (3 weeks) time points following experimental metastasis assays and subjected to immunohistofluorescence staining with anti-S100a8 (red) or anti-neutrophil elastase (NE) (green) antibodies. The number of S100a8-positive cells (A) or NE-positive cells (B) per field was quantified. (C) Positivity of neutrophil staining (expressed as a percentage of S100a8 and NE double-positive cells over the total number of S100a8-positive cells) was quantified within each region of interest. While the number of s100a8- and NE-positive cells increased during tumor progression (s100a8 distal early vs. distal late, P <0.001; NE distal early vs. distal late, P = 0.021; s100a8 tumor early vs. tumor late, P <0.001; NE tumor early vs. tumor late, P <0.001), a decrease in the proportion of neutrophils comprising the s100a8⁺ infiltrate was routinely observed in the tumor or the distal region as tumor progressed (distal early vs. distal late, P = 0.019; tumor early vs. tumor late, P = 0.006). In contrast, no changes were observed in the margin of the lesions.