Poly(A:U) induces LIC expansion in vivo. (A) Representative flow plots depicting early precursor B-cell populations (Hardy fractions [Fr] A, B, and C/C′) from the spleen and BM of PBS- or Poly(A:U)-treated mice. (B) FrA, FrB, and FrC/C′ and mature B cells (B cell) were quantified by flow cytometry from PBS- and Poly(A:U)-treated mice. Cell counts were quantified using CountBright beads and results pooled from at least 3 individual experiments (Dunnett multiple comparison test). (C) Representative flow cytometry plots depicting BrdU⁺ LIC in the spleen and BM from PBS- or Poly(A:U)-treated mice. (D) Early BCP proliferating in the BM of Poly(A:U)-treated compared with PBS-treated control mice, expressed as % BrdU⁺ B220⁺CD43⁺ cells. Results are pooled from 2 individual experiments (Šídák multiple comparisons test). Bars represent mean ± SD; ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001; ns.