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Hwang, Inkyu; Shen, Xuefei; Sprent, Jonathan
Proceedings of the National Academy of Sciences - PNAS, 05/2003, Volume: 100, Issue: 11Journal Article
T cell stimulation usually requires direct contact with viable antigen-presenting cells (APCs). However, we show here that small exosome-like membrane vesicles shed from APCs can be recognized by$na\ddot{\imath} ve\>CD8^+$T cells in the absence of viable APCs. T cell antigen receptor-dependent binding of vesicles by CD8+cells is MHC class I/peptide-specific and requires that the vesicles coexpress intercellular adhesion molecule 1 (ICAM-1, CD54), although not B7 (B7-1). In the absence of B7, T cell binding of vesicles is nonimmunogenic. By contrast, vesicles expressing both ICAM-1 and B7 are strongly immunogenic and cause purified APC-depleted CD8+cells to mount peptide-specific proliferative responses and differentiate into effector cells.
