The mechanisms by which autoimmune diseases are triggered and by which the activation of autoreactive T cells is initiated and maintained are not yet fully understood. As the most potent antigen presenting cells (APC), and also being responsible for antigen transport as well as primary sensitisation of T cells, dendritic cells (DC) are capable of breaking the state of self-ignorance and inducing aggressive autoreactive T cells. In the development of autoimmune diseases, different types of DC exhibit distinct properties for inducing Th1/Th2 cell responses. Appropriate cytokines can convert immunogenic DC to tolerogenic DC. Utilizing the possibility to promote the tolerogenic effects of DC, a new therapeutic tool might soon become available to treat multiple sclerosis and other autoimmune diseases.