CD8+ T cell cross-priming via transfer of proteasome substrates. Journal   Science. Citation   Science. 304(5675):1318-21 Publication date   2004 May 28 Authors   Norbury CC Basta S Donohue KB Tscharke DC Princiotta MF Berglund P Gibbs J Bennink JR Yewdell JW Investigators   Christopher Norbury Grant agencies   National Institute of Allergy and Infectious Diseases Grants   NIAID AI-056094-01 MeSH headings   Acetylcysteine Antigen Presentation Antigens CD8-Positive T-Lymphocytes Cross-Priming Cysteine Endopeptidases Multienzyme Complexes MeSH qualifiers   analogs & derivatives immunology metabolism Abstract   "Cross-priming" describes the activation of naïve CD8+ T cells by professional antigen-presenting cells that have acquired viral or tumor antigens from "donor" cells. Antigen transfer is believed to be mediated by donor cell-derived molecular chaperones bearing short peptide ligands generated by proteasome degradation of protein antigens. We show here that cross-priming is based on the transfer of proteasome substrates rather than peptides. These findings are potentially important for the rational design of vaccines that elicit CD8+ T cell responses.