MC38 tumor cells were cultured and transferred subcutaneously (s.c.) into Prdm1f/f and Prdm1f/f CD19cre recipient mice. On DPI 18, inoculated MC38 tumors were collected from 11 recipients in each group. Immune cells were enriched by percoll gradients (30% and 70%) first, then sorted as single B220+ cells and single CD138+ cells from living cells (the viability dye negative population) using the Sony MA900 cell sorter. The sorted cells were combined and resuspended in 10% FBS, PBS buffer. Then samples were processed with the VDJ and GEX library preparations. Libraries were loaded onto 100-cycle flowcells for sequencing using the NextSeq2000 (Ilumina) and sequenced as follows: read1 = 26 cycles, i7 index = 10 cycles, i5 index = 10 cycles, read 2 = 90 cycles. 1400 cells were targeted per sample ("BLIMP", "CTRL") with 6,000 reads/cell for VDJ/B cell enriched library, and 24,000 reads/cell for 5' GEX library.