(A) Glomerulus with crescent in C57Bl/6 mouse (control) and normal appearance of glomerulus in kidney of CCL19-Cre x iDTR mouse in NTN following FRC depletion (H&E). Scale bar 50 µm. (B) Percentage of crescentic glomeruli in kidneys at Day 7 decreases following FRC depletion (Control: n=4, mean 44.75%±8.057, range 25–60%, median 47.008545%; CCL19-Cre x iDTR: n=5, 24.14%±4.127, 13.33333–32%, median 28.57143%) (p=0.1111). (C) BUN at Day 7 is significantly reduced in mice following FRC depletion (Control: n=4, 38.95±1.109, 36.51896–41.79039, median 38.750875; CCL19-Cre x iDTR: n=5, 28.66±3.7, 15.1556–35.33628, median 29.75764) (D) Immunohistochemistry of kidney shows decreased infiltration of CD3+ T cells (red, top row) and F4/80+ macrophages (red, bottom row) in kidney in CCL19-Cre x iDTR kidney, as reflected by cell count quantification in (E) (CD3+ T cells: Control: n=4, 19.25±2.529, 13–25, median 19.5; CCL19-Cre x iDTR: n=5, 8.6±1.327, 4–12, median 9) (F4/80+ macrophages: Control: n=4, 80.5±8.78, 63–98, median 80.5; CCL19-Cre x iDTR: n=5, 40.2±5.352, 22–50, median 47). Glomerulus marker nephrin (green), nuclear marker DAPI (blue). Scale bar 50 µm. (F) FRC depletion results in decreased deposition of ER-TR7+ (red) fibers, reduced laminin fiber (green) formation, and decreased invasion of LYVE1+ lymphatic endothelial cells (green). Scale bar 100 µm. (G) FRC depletion results in decreased density of ER-TR7+ fibers (red) surrounding PNAd+ HEV (green), which contains fewer pockets. Scale bar 50 µm. (H) CD4+ effector memory cell (CD4+CD44highCD62Llow) and Th17 (CD4+IL-17A+) cell populations decrease in KLN following FRC depletion (CD4+ effector memory cells: Control: n=4, 176993±40796, 80220–267238, median 180256; CCL19-Cre x iDTR: n=5, 20438±7769, 4281–39617, median 15377) (Th17 cells: Control: n=4, 5174±812, 3529–6656, median 5254.5; CCL19-Cre x iDTR: n=5, 2405±808.9, 323–3994, median 3062) (p=0.0635 for Th17 cells). *p<0.05. FRC: fibroblastic reticular cell, NTN: nephrotoxic serum nephritis, H&E: hematoxylin and eosin, BUN: blood urea nitrogen. Data in graphs are presented as means (horizontal bar) ± SEM (vertical bars).