V(D)J, Ig κ, and E_μ SHM in 3′RR-deficient and WT mice. (A) Expressed IgH V(D)J regions and Cκ regions from B220⁺PNA^highFas⁺ cells were cloned and sequenced. Number of mutated sequences, number of mutations, and mutation frequency are reported. Clonally related sequences were excluded. Statistical differences were investigated with the Mann–Whitney U test. Peyer’s patches from 10 3′RR-deficient and 12 WT mice were used for B220⁺PNA^highFas⁺ cell purification. Mice were 8 wk old, and immunizations were performed orally with sheep red blood cells for 2 wk and intraperitoneally with 10 µg LPS for 3 d. (B) Mutation analysis in expressed IgH V(D)J regions of 3′RR-deficient mice and WT mice. (left) Expressed IgH V(D)J region B220⁺PNA^highFas⁺ cells were cloned and sequenced (12 WT and 10 3′RR-deficient mice). (right) Mutations found in four separated WT mice. (C) Mutation analysis in expressed Cκ regions of 10 3′RR-deficient and 12 WT mice. (D) Mutation analysis in the 5′ end of S_μ. B splenocytes from five 3′RR-deficient and five WT mice were used for B220⁺PNA^high cell purification. Mice were 8 wk old, and immunizations were performed orally with sheep red blood cells for 2 wk and intraperitoneally with 10 µg LPS for 3 d.