TNF-α is necessary for LIC expansion in neonates. Representative flow cytometry plots (A) and cumulative results (B) from independent experiments showing TNF-α production by neonatal and adult B220⁺/CD19⁺/MHC CII⁺ lymphoid cells (left) and B220^–/CD11c^–/CD11b⁺ myeloid cells (right); paired t test. (C) In vivo impact of cytokine (TNF-α or IL-10) neutralization on LIC numbers in 6-day-old Eμ-Ret pups injected with Poly(A:U). Cell counts in harvested organs were quantified using CountBright beads. (Dunnett multiple comparison test; bars represent mean ± SD). Pooled results are from at least 3 individual experiments. ∗P < .05; ∗∗P < .01, ns.