Fig. 8.

Neutrophil gelatinase-associated lipocalin (Ngal) immunoreactivity. Kidney Ngal (green) immunolabeling staining at baseline and during infection labeled for collecting ducts with aquaporin 2 (red). In the Car2^+/+ cortex at baseline (A) and during infection (B), occasional proximal tubules demonstrated low immunoreactivity (arrows), but collecting ducts were negative (arrowheads). At baseline (C), no Car2^+/+ medullary staining for Ngal was found in collecting ducts (arrowhead), but during infection (D), some collecting ducts stained for Ngal (arrows), whereas others did not (arrowheads). In Car2^−/− mice at baseline (E) and during infection (F), cortical Ngal immunoreactivity was present in occasional proximal tubules (arrows) but not collecting ducts (arrowheads). At baseline (G), some occasional Car2^−/− medullary collecting ducts immunolabeled with Ngal, with the intensity of the fluorescence increasing during infection (H). Areas of marked Ngal staining were scattered, usually in the area of neutrophil aggregations (*). Aquaporin-2-positive cells were also positive for Ngal (arrows) in Car2^+/+ (I) and Car2^−/− (J) infected medullas, indicating that principal cells can express Ngal in response to infection. Magnification: ×40 in A–D and ×100 in I and J. Three sections from 2 mice per genotype and infection status were reviewed. All scale bars = 20 μm.