Probing lymphocyte biology by genomic-scale gene expression analysis

The identity and abundance of mRNA species within a cell dictate, to a larg e extent, the biological potential of that cell. Although posttranscription al mechanisms modify protein expression in critical ways, cellular differen tiation requires key changes in gene transcription, as evidenced by the pot ent phenotypes that result from disruption of transcription factor genes in mice. It is now possible to assess the mRNA profile of a cell globally usi ng recently developed genomics techniques. This review focuses on the poten tial of cDNA microarrays to define gene expression in lymphoid cells, a fie ld which is in its infancy. Examples of cellular activation genes and cytok ine inducible genes discovered using this technology are presented but thes e represent only a taste of the fruit that this new technology will ultimat ely bear. Gene expression profiles should provide essential new insights in to lymphocyte differentiation and activation, the pathogenesis of immune di sorders, and the molecular abnormalities in lymphoid malignancies.