Quantitative gene expression (QGE) was defined as being at 1 of 5 levels. A gene was “−” if all the samples in the group had an absent absolute call (AC), “+” when all samples had present AC and average difference call (AD) < 1000, “++” when all samples had present AC and AD between 1000 and 5000, “+++” when all samples had present AC and AD between 5000 and 10 000, and “++++” when all samples had present AC and AD > 10 000. Up-regulated LDGs (n = 7) in the tonsil BC to tonsil PC transition are listed first. A hierarchy in the listing of genes was established such that QGE (5 expression levels) increases from top to bottom and from left to right for up-regulated genes and increases from top to bottom and decreases from left to right for down-regulated genes. Although the expression patterns of bone marrow PCs were not used to derive the list of EDGs, the gene expression levels in these cells are provided for reference.

Accession numbers are GenBank accession numbers corresponding to the Affymetrix GeneChip probe set for the given gene. Symbols are HUGO-approved gene symbols. TBCs indicates CD19-enriched tonsil BCs; TPCs, CD138-enriched tonsil PCs; BPCs, CD138-enriched bone marrow PCs.