Maturation of splenic EYFP⁺PCs on B-cell depletion. (A) Heatmap representation of multiplex single-cell RT-PCR performed with the Fluidigm Dynamic Array on PBs, Spl-PCs, anti-CD20 PCs, and BM-PCs using 18 genes (PB genes: Mki67, Chek1, Bub1, Aurka, Rrm2b, Ccnd2, Bcl2l11, and Cxcr3; LLPC genes: Tesc, Klf6, Tnfaip3, Bcl2, Runx2, Tnfrsf17, Nfkb2, Tox2, Tmem176b, and Mt2) discriminating PBs from LLPCs. Analysis was restricted to cells expressing B2m and the Prdm1 PC master gene. Columns represent individual gene probes, and rows represent single cells, with color relative to the cycle threshold expression value (scale bar at bottom). (B) Principal component analysis of 441 individual cells analyzed for the expression of 18 diagnostic genes. Each dot represents a single cell: gray, splenic ASCs generated 3 days after a third immunization (boost); blue, PCs 3 months after immunization (Spl-PCs); orange, PCs at the nadir of B-cell depletion (anti-CD20 PCs); green, BM-PCs 3 months after the second immunization (same animals as Spl-PCs). Multiplex single-cell RT-PCR performed with the Fluidigm Dynamic Array involved 140 cells per group (C) Percentage of individual cells expressing n diagnostic PC genes in each population (boost [gray], Spl-PCs [blue], anti-CD20 PCs [orange], BM-PCs [green]). (D) Cumulative percentage of cells expressing n or more PC genes in each group.