Th1-and Th2-cell commitment during infectious disease: asymmetry in divergent pathways

The development of T helper 1 (Th1) versus Th2 cells is a major branch poin t in the immune response. It is an important determinant of whether the res ponse to an infectious pathogen will lead to protection of the host or diss emination of the disease. Recent studies have suggested that this process i s governed by distinct sets of signals provided by dendritic cells upon int eractions with specific infectious agents. A model is proposed that links t ogether the pathogen,the innate response and Th-cell polarization.