A growing body of evidence indicates that the kidneys contribute substantially to immune defense against pathogens in the urinary tract. In this issue, Paragas et al. report that α–intercalated cells (A-ICs) within the nephron collecting duct sense infecting Gram-negative bacteria, resulting in simultaneously secretion of the iron chelating protein lipocalin 2 (LCN2) and protons, which acidify the urine. A-IC–specific LCN2 and proton secretion markedly reduced the ability of infecting uropathogenic
Yuxuan Miao, Soman N. Abraham
A-ICs defend against urinary pathogens.