CD5 and B-cell chronic lymphocytic leukemia: Nevertheless, our preliminary analysis of a published transcriptomic dataset (Gene Expression Omnibus accession number: GSE36907) indicated that the CD22 mRNA level is lower in the B cells of CLL patients than in the CD5+ B cells of healthy donors (i.e., the putative normal counterpart of CLL B cells (24)), suggesting that transcriptional regulation may play a major role in CD22 protein expression.