EN
The phenomenon of antigen presentation can be divided into three stages. 1/ antigen uptake (recognition and internalization), which first of all concerns exogenous antigens; 2/ intracellular enzymatic antigen processing and protein degradation followed by peptide loading of presenting molecules; 3/ exocytosis of the antigen presenting molecules complex containing: a) MHC class II /exogenous antigens; b) MHC class I/endogenous antigens; c) MHC class I/exogenous antigens (so-called cross-presentation); d) CD1 ? lipids. This review presents the main stages of intracellular transport and the traffic of MHC molecules, which are believed to be different in dendritic cells (DC), in comparison with other antigen presenting cells, and enable DC to play the unique role in the initiation of immune response and the induction of tolerance.