Figure 4. Neonatal CD71⁺ cells prevent aberrant immune cell activation in tissue that is rapidly colonized with commensal microbes.

a, TNF-α production by intestinal immune cells from 8-day-old mice treated with anti-CD71 antibody (or isotype control antibody (rat IgG)) on days 5 and 6. b, TNF-α production by cells recovered from the indicated tissues after anti-CD71 antibody treatment of neonatal mice (normalized to the values from isotype-control-antibody-treated neonatal mice). c, The number of recoverable bacteria (CFU) from intestine (brown), spleen (red) and lung (blue) of fetal (embryonic day (E) 18.5) and neonatal mice in the indicated age (days post parturition (PP)) after housing with unsupplemented drinking water or drinking water containing antibiotics (ampicillin, gentamicin, metronidazole, neomycin and vancomycin) from E14.5 (n=6–18 mice per time point). d, TNF-α production by cells recovered from the indicated tissues of neonatal mice sustained on antimicrobial therapy and treated with anti-CD71 antibody (normalized to the values from isotype-control-antibody-treated neonatal mice sustained on antimicrobial therapy). e, The proportion of splenocytes that are CD71⁺TER119⁺ in 8-day-old conventional and germ-free mice. f, TNF-α production by cells recovered from the indicated tissues of germ-free neonatal mice treated with anti-CD71 antibody (normalized to the values from isotype-control-antibody-treated germ-free neonatal mice). Each point represents data from an individual mouse, and the data are representative of three independent experiments. Error bars, mean±s.e.m.