Efficient generation of indels in primary mouse B cells by CRISPR/Cas9. (A) Targeting scheme for Igh (crIgH) and Igk crRNA guides (crIgK₁, crIgK₂). (B) Experimental setup for C–E. Primary mouse B cells were cultured for 24 h in the presence of anti-RP105 antibody and then transfected with Cas9 RNPs and analyzed at the indicated time points. gDNA, genomic DNA. (C) Flow-cytometric plots of cultured B cells at the indicated time points after transfection. Control uses an irrelevant crRNA targeting the HPRT gene. (D) Quantification of C, percentage of Igκ⁻ Igλ⁻ B cells by flow cytometry (right y axis), and percentage of cells containing indels in the Igkc exon by TIDE analysis (left y axis). Control bars include irrelevant HPRT-targeting crRNAs or a scramble crRNA without known targets in the mouse genome. (E) Percentage of cells containing indels in the J_H4 intron by TIDE analysis after targeting with crIgH or control. Bars indicate mean ± SEM in two (TIDE) or four (flow cytometry) independent experiments.