PBMC cells were isolated from fresh whole human blood using Ficoll-paque. Dead cells were labelled in PBS with a cell viability dye. Cells were labelled for FACS using CD19 and CD3 in PBS. Single, live, CD3-CD19+ B cells were isolated by FACS using a FACSAria III. Library was performed according to the manufacter's instructions (single cell 3' v3 protocol, 10x Genomics).