Antigen presentation by macrophages harboring intravesicular pathogens.

Resting macrophages can be host cells for the replication of several protozoan parasites and bacteria. Upon activation, infected cells mobilize potent microbicidal mechanisms that eliminate the intracellular pathogen. This transition from a resting to an activated state is mediated by the interaction 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 presentation in infected macrophages from a cell biological point of view, a perspective that has important implications for the design of subunit vaccines.