Antigen presentation by macrophages harboring intravesicular pathogens

Resting macrophages can be host cells for the replication of several protoz oan parasites and bacteria. Upon activation, infected cells mobilize potent microbicidal mechanisms that eliminate the intracellular pathogen. This tr ansition from a resting to an activated state is mediated by the interactio n with specific T cells that recognize pathogen-derived peptides complexed to major histocompatibility complex (MHC) molecules at the surface of host cells. In this review, Peter Overath and Toni Aebischer discuss antigen pre sentation in infected macrophages from a cell biological point of view, a p erspective that has important implications for the design of subunit vaccin es.