Dendritic cell subsets and the regulation of Th1/Th2 responses

Cells of the dendritic family are suited to perform two distinct functions at two discrete locations. In the peripheral tissues, dendritic cells (DC) act as sentinels for "dangerous" antigens. They then migrate into the lymphoid organ, where they initiate activation of T lymphocytes which are specific for these antigens. During their migration, DC shift from an antigen-capturing mode to a T cell sensitizing mode. In addition to switching on the immune response, subtypes of DC appear to influence the character of T cell differentiation, i.e. the Th1/Th2 balance. We will review the cellular and molecular bases of Th1-Th2 development by DC subsets, and will focus primarily, although not exclusively, on mouse DC.