Kinetics of antigen-induced phenotypic and functional maturation of human monocyte-derived dendritic cells

Dendritic cells (DCs), a critical component of innate immunity, are the mos t potent APCs. When DCs mature, they can elicit strong T cell responses. We studied the kinetics of Ag-induced phenotypic and functional maturation of human monocyte-derived DCs using an in vitro T cell-independent culture sy stem. With this model, we herein show that an Ag that has recently or repet itively been exposed ("exposed Ag") rapidly induces a high level of maturat ion; however, an Ag that has never or only remotely been exposed ("unexpose d Ag") slowly induces a low level of maturation. The kinetics of Ag-induced maturation of DCs possibly implies a novel mechanism for immunological mem ory that would provide maximal host protection from repetitively invading p athogens in the environment.