Dendritic cells (DCs) are the sentinels of the immune system. They sense, process, and present antigens to T lymphocytes orchestrating the immune response. The discovery of DCs granted the Nobel Prize for Ralph Steinman, who noticed the presence of rare cells in a culture of mice adherent cells with a distinct stellate morphology [ ]. Years later, these cells were shown to express high amounts of major histocompatibility complex class II (MHC-II) molecules, and, even though in very low numbers, they revealed to be the cells responsible for activation and stimulation of naive T lymphocyte [ ]. DCs not only activate and subsequently polarize lymphocyte but also can have a tolerogenic role, which is dependent on the factors derived from the surrounded microenvironment [ ] and is crucial for the outcome of infectious diseases and autoimmunity by protecting the body from immune-mediated tissue damage. This tolerogenic property is also a target of manipulation by tumor cells to evade the immune response. Thus, understanding the precise regulation of DC function mediated by the different stimulus, such as cytokines and other mediators, remains the goal of numerous studies aiming at skewing T lymphocytes polarization in vaccination protocols for both cancer and infectious diseases.
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