The term cross-presentation denotes the ability of certain antigen-presenting cells to take up, process and present extracellular antigens with MHC class I molecules to CD8 T cells (cytotoxic T cells). Cross-priming describes the stimulation of naive cytotoxic CD8+ T cells by this process. This process is necessary for immunity against most tumors and against viruses that do not infect antigen-presenting cells.
It is also required for induction of cytotoxic immunity by vaccination with protein antigens, for example in tumour vaccination.
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