Outside looking in: the inner workings of the crosspresentation pathway within dendritic cells

The entry of exogenous antigen into the MHC class I-restricted crosspresentation pathway can contribute to CD8+ T cell tolerance and immunity, in particular to peripheral self-antigens or selected viruses and bacteria showing restricted tissue tropism. Dendritic cells are the key crosspresenting cells and, as such, they are thought to carry specialized machinery dedicated to this purpose. Two recent papers describe intracellular components tailored to the dendritic cell crosspresentation pathway.