Direct stimulation of naive T cells by membrane vesicles from antigen-presenting cells: distinct roles for CD54 and B7 molecules.
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 naïve 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.
Department of Immunology, IMM4, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Inkyu
I
Hwang
Xuefei
X
Shen
Jonathan
J
Sprent
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology*; D018122:B7-1 Antigen / Q000276:immunology*; D002462:Cell Membrane / Q000276:immunology; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology*; D008024:Ligands; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013601:T-Lymphocytes / Q000276:immunology*
D018122:B7-1 Antigen; D008024:Ligands; D018799:Intercellular Adhesion Molecule-1