A genomic view of lymphocyte development

RNA expression profiles of consecutive stages of mouse and human B-cell precursors, and of mouse T-cell precursors, from DJ re-arranged states to mature lymphocytes have been generated using high-density oligonucleotide arrays. Approximately 10% of all genes present on the arrays are differentially expressed across all cellular stages of each of the lineages. Approximately half of these are differentially expressed during both T-cell and B-cell differentiation. Many of the genes that are shared are involved in cell cycle regulation and DNA replication, whereas most of the signaling and adhesion molecules and transcription factors are expressed in a lineage-specific manner. Comparable stages of the T-and B-lineage developmental programs share only a few genes. By contrast, homologous genes differentially expressed during both human and mouse B-cell development have very similar expression patterns.