Fig. 5.

VH replacement is detected in pro-B cells. (A) Representative flow cytometric analysis of BM cells in V_HQ52^NT-HT mice and age-matched littermate controls (IgH^WT). Numbers indicate frequencies of gated progenitor (B220⁺Igκ⁻) and sIg⁺ (B220⁺Igκ⁺) B cells. (B) Absolute number of BM pro-B (B220⁺Igκ⁻CD43⁺CD25⁻) and pre-B (B220⁺Igκ⁻CD43⁻CD25⁺) cells in representative cases of controls (IgH^WT) (n = 5) and V_HQ52^NT-HT mice (n = 4) as assessed by flow cytometric analysis. (C) V_H gene use in VH replacements cloned from pro-B cells of V_HQ52^NT-HT mice. Numbers within pie segments indicate frequency of germ-line V_H genes involved in VH replacements (n = 52). (D) Frequency of unique VH replacements cloned from BM pro-B cells of V_HQ52^NT-HT mice, assessed by CDR3 sequence analysis. VH replacements carrying the same V_H gene were grouped. (E) Frequency, respectively, of IF and OF VH replacements cloned from pro-B cells of V_HQ52^NT-HT mice. Numbers refer to percentage of unique VH replacements (n = 30).