Fig 1: Reduction of FRC progenitors in the aged lymph nodes. Skin-draining (sdLN) and mesenteric (mLN) lymph nodes from young and aged WT mice were depleted of CD45+ cells before analysis by flow cytometry. (A). Gating of CD45-CD35-B220-ICAM-1+ stroma into fibroblastic reticular cells (FRCs), lymphatic endothelial cells (LECs), blood endothelial cells (BECs), and double negative cells (DNs) in the sdLN and mLN of young and aged mice. (B). Frequency of FRCs, LECs, BECs, and DNs within young and aged sdLN and mLN stroma. (C). Number per lymph node of FRCs, LECs, BECs, and DNs within young and aged sdLN and mLN stroma. (D). Gating of MAdCAM-1- FRCs into VCAM-1lo, VCAM-1int, and VCAM-1hi subsets in the sdLN and mLN of young and aged mice. (E). Frequency of VCAM-1lo, VCAM-1int, and VCAM-1hi FRC subsets within young and aged sdLN and mLN stroma. Relative fluorescence intensity (RFI) of surface markers (F). LTBR and (G). SCA-1 on VCAM-1lo, VCAM-1int, and VCAM-1hi FRC subsets within young and aged sdLN and mLN stroma. RFI normalized to expression on young VCAM-1hi FRCs. Data is representative of lymph nodes retrieved from 6 young and 6 aged mice. Analyzed by two-way ANOVA with adjustment for multiple comparisons, p-values: ns, not significant; * < 0.05, ** < 0.01, *** < 0.001, **** < 0.0001.