Figure 5.

Neutrophil recruitment into the mammary gland and across the alveolar epithelium is IL18 dependent. Mammary glands of lactating IL18R −/− (CXCR2 −/−) mice were infused with 10 μg LPS. H&E staining of formalin-fixed mammary tissues 24 h after LPS inoculation (A−C). Neutrophil recruitment into the mammary gland is markedly reduced (A and B). Recruited neutrophils are seen in capillaries and interstitium and trapped in between alveolar epithelial cells (arrows in C which is an inset of B) unable to transverse the epithelium to the milk space. Reduced neutrophil recruitment to the mammary gland was also indicated by the MPO assay (D). Significantly lower relative (LPS to PBS-challenged gland) MPO activity was observed in the mammary glands of IL18R −/− mice compared with wt Balb/c mice. Data are mean and S.E., n ≥ 6/group and p values represent a comparison between groups using the Student t-test. Scale bars 200 μm (A and B), 50 μm (C). (A color version of this figure is available at www.vetres.org.)