Delivery of exogenous protein antigens to major histocompatibility complex class I pathway in cytosol.

A fragment of anthrax lethal factor possesses the interesting function of delivering recombinant protein antigens through the classical major histocompatibility complex (MHC) class I pathway. This region of the lethal factor lacks the domain associated with anthrax cytotoxicity and functions independently of its binary partner, protective antigen. Experiments that used inhibitors at different steps of the MHC class I pathway supported this hypothesis. Application of this discovery to current T cell assays allows for the measurement of cytotoxic T lymphocyte function without resorting to live vectors and provides a useful new tool to design and test T cell-dependent vaccines.