Natural killers: the bad guys in fibrosis?

Immune cells infiltrating the tubulointerstitium critically contribute to the progression of chronic kidney disease. In this issue of Kidney international, Law et al. provide first evidence for a role of natural killer cells in the perpetuation of tubulointerstitial fibrosis in human renal disease. By detailed flow cytometric characterization of leukocytes isolated from kidney biopsies of chronic kidney disease patients, they define accumulation of natural killer cells as a feature of fibrotic kidney tissue and provide insight into potential mechanisms of how these cells might promote chronic kidney inflammation.