library_construction_protocol: PBMC were isolated by ficoll density gradient from 2 anonymous platelet donor leukapheresis packs naïve B cells were isolated by magnetic assisted cell sorting via negative selection. CD5 expressing B cells were enriched by positive selection for CD5 protein and then added back into a 1:1 ratio with CD5 negative B cells. Libraries were prepared using the 10X Genomics Chromium Single Cell 3' v3 kit and Chromium i7 Multiplex Kit.