The role of IRF-4 in B and T cell activation and differentiation.

Appropriate activation and differentiation of lymphocytes are critical for effective immune responses. These processes are normally guided by exposure of lymphocytes to different stimuli, which need to be appropriately integrated in order for lymphocytes to proceed along their activation and differentiation pathways. Although the early steps in lymphocyte activation have been studied extensively, the downstream effectors of these activation pathways and the basic mechanisms employed by lymphocytes to integrate the information provided by different activation stimuli are not fully characterized. Interferon (IFN) regulatory factor-4 (IRF-4) is a recently described member of the IRF family of transcription factors whose expression is largely restricted to lymphocytes. Genetic studies have indicated that IRF-4 is critical for the function of mature T and B cells. Here we review the role of IRF-4 as a downstream effector and potentially an integrator of lymphocyte responses.