ChIP-seq and ChIP-qPCR analysis of histone modifications

For ChIP-seq analysis, sorted activated B cells and plasmablasts after 4 days of LPS stimulation were used for chromatin immunoprecipitation (ChIP) with histone modification-specific antibodies (see antibody section above), as described in detail¹³. The ChIP efficiency was quantified by real-time PCR analysis and about 1-5 ng of ChIP-precipitated DNA was used for library preparation. The ChIP-qPCR analysis of histone modifications (Fig. 2g,h) was performed using OHT-treated WEHI-Blimp1-ER^T2 cells, and the precipitated DNA was subjected to the qPCR quantification, using region-specific primers listed in Supplementary Table 6. The specific enrichment was calculated as the DNA amount relative to the input followed by normalization against the Tbp promoter.