Similarity measurements of B cell receptor repertoire in baseline mice showed spectrum convergence of IgM

Background The B cell receptor (BCR) repertoire is highly diverse among individuals. Poor similarity of the spectrum among inbred baseline mice may limit the ability to discriminate true signals from those involving specific experimental factors. The repertoire similarity of the baseline status lacks intensive measurements. Results We measured the repertoire similarity of IgH in blood and spleen samples from untreated BALB/c and C57BL/6J mice to investigate the baseline status of the two inbred strains. The antibody pool was stratified by the isotype of IgA, IgG and IgM. Between individuals, the results showed better convergence of CDR3 and clonal lineage profiles in IgM than in IgA and IgG, and better robustness of somatic mutation networks in IgM than in IgA and IgG. It also showed that the CDR3 clonotypes and clonal lineages shared better in the spleen samples than in the blood samples. The animal batch differences were detected in CDR3 evenness, mutated clonotype proportions, and maximal network degrees. A cut-off of 95% identity in the CDR3 nucleotide sequences was suitable for clonal lineage establishment. Conclusions Our findings reveal a natural landscape of BCR repertoire similarities between baseline mice and provide a solid reference for designing studies of mouse BCR repertoires.

Automated summary

The study measured the B cell receptor (BCR) repertoire similarity in blood and spleen samples from BALB/c and C57BL/6J mice, finding better convergence in IgM compared to IgA and IgG, and better robustness in IgM somatic mutation networks. It also showed better sharing of CDR3 clonotypes and clonal lineages in spleen samples than in blood samples. Differences in CDR3 evenness, mutated clonotype proportions, and maximal network degrees were detected between animal batches.