Developmental aspects of dendritic cells in vitro and in vivo

Dendritic cells (DC) are potent antigen presenting cells that possess the unique ability to stimulate naive T-cells. By studying DC derived from various tissues it has been shown that the morphology, phenotype and function of DC alter as they undergo a complex process of maturation. DC are derived from bone marrow progenitors and circulate in the blood as immature precursors prior to migration into the peripheral tissues. Within tissues DC are specialised in the taking up and processing of antigen so that it may be presented on MHC class II molecules. Upon appropriate stimulation tissue DC undergo further maturation and migrate to secondary lymphoid tissue where they present antigen to T-cells and induce an immune response. Studies of DC maturation in vitro have defined the cytokines regulating their development from CD34+ myelomonocytic progenitors as well as from more mature peripheral blood precursors. An alternative pathway of differentiation from thymic precursors has also been described. As a result of these studies, DC may now be generated and manipulated ex-vivo for clinical applications in oncology, autoimmune disease and transplantation.