Fig. 1: Neutrophils are the major cellular source of TGFβ1 in BM from aged mice.

a Expression levels of TGFβ1 in protein lysates from bone (with BM flushed out), BM cells (BMC), and BM plasma from one leg from young (2–4-mon-old) and aged (18–22-mon-old) male C57 mice using ELISA. Mean±SD (n = 7 biologically independent male mice/group). b Surface and intracellular expression of TGFβ1 tested by FACS in BM cells from 4- and 22-mon-old C57 mice. Mean ± SD (n = 7 biologically independent male mice/group). c Enrichment of TGFβ1⁺ BM cells in CD11b⁺Gr1⁺ myeloid cells and percentages of various types of BM cells expressing TGFβ1 in BM. Mean ± SD (n = 4 biologically independent male mice). d, e FACS analysis of Ly6C⁺ and Ly6G⁺ subpopulations in TGFβ1⁺CD11b⁺ myeloid cells with TGFβ1 surface and intracellular expression in BM from 4- and 22-mon-old C57 mice, and frequencies (f, g) and numbers (h, i) of monocytic (Ly6C^hi6G^-), granulocytic (Ly6C^-6G⁺) and intermediate-stage (Ly6C^lo6G^-) cells in TGFβ1⁺CD11b⁺ myeloid cells in BM. Mean±SD (n = 7 biologically independent male mice/group). j Frequencies of TGFβ1⁺CD11b⁺Ly6C^-6G⁺ cells in peripheral blood, mesenteric lymph nodes, and spleen. Mean ± SD (n = 5 biologically independent male mice/group). k H&E-stained Ly6C⁺ and Ly6G⁺ subpopulations from TGFβ1⁺CD11b⁺ myeloid cells following FACS and cyto-spinning. Bar = 10 μm. Analyses: Student’s two-sided unpaired t test. Source data are provided as a Source data file.