Fig. 8.

IgH allelic inclusion is observed in a small fraction of V_HQ52^NT mature B cells. (A) Representative flow cytometric determination of sIgA/IgM double producers within, respectively, gated B2 (CD19⁺B220⁺) and B1 (B220^loCD19^hi) B cells in the peritoneal cavity of V_HQ52^NT-HT mice (n = 5). Numbers indicate frequency of boxed sIgA/sIgM double producers. (B) Average frequency of sIgA/sIgM double producers among the indicated B-cell subsets in the peritoneal cavity of V_HQ52^NT-HT mice (n = 5). (C) V_H gene use in purified IgM⁺ splenic B cells of V_HQ52^NT-HT mice, assessed by genomic PCR using primers annealing to V genes of the main V_H families including Q52. Numbers indicate frequency of IgH rearrangements (n = 56) consisting of the indicated V_H genes. (D) Intracellular flow cytometric determination of IgA H expression in the indicated subset of SP B cells in controls (IgH^WT) and V_HQ52^NT-HT mice.