Different B cell subsets were sorted and gene expression analysis was performed on sorted populations. The top 100 genes that were overexpressed in plasmablasts compared with memory B cells (left column) and in plasmablasts compared with proposed B-1 cells (right column) are listed, ranked in descending order of difference in expression. Genes depicted in bold have been associated with plasma cell differentiation^23-25  or have been associated with a plasma cell–specific biological network, as defined by Jourdan et al, 2009.²⁵