Thus, while T cells contribute some of these cytokines, it is likely that nonimmune cells, such as tubular epithelial cells (which are known to produce TGF-β1 and GM-CSF in renal fibrosis; refs. 31, 32), may also help induce Siglec-F+ neutrophils by generating inflammatory cytokines. This evidence concerns the gene CSF2 and renal fibrosis.