Dendritic cell lineage, plasticity and cross-regulation

Dendritic cells (DCs) are professional antigen-presenting cells that have a n extraordinary capacity to stimulate naive T cells and initiate primary im mune responses. Here we review progress in understanding the additional fun ctions of DCs in regulating the types of T cell-mediated immune responses a nd innate immunity to microbes. In addition, evidence for the existence of myeloid and lymphoid DC lineages and their different functions are summariz ed. We propose that the diverse functions of DCs in immune regulation are d ictated by the instructions they received during innate immune responses to different pathogens and from their evolutionary lineage heritage.