Stability and commitment in T helper cell development

Specialized effector activities that are required to eliminate various path ogens involve cytokines produced by specialized CD4(+) T cells subsets, dog matically termed Th1 and Th2 cells. Despite some oversimplifications, this paradigm is useful for organizing the complex pathways that control forward and backward movements along the road of T cell differentiation, Effective immune memory relies, in part, on the maintenance of the T helper phenotyp e. This review will address basic issues that relate to the maintenance or reversibility of Th1/Th2 states within the CD4(+) T cell lineage.