title: The small GTPase Rac2 controls phagosomal alkalinization and antigen crosspresentation selectively in CD8(+) dendritic cells.
abstract: A unique subpopulation of spleen dendritic cells (DCs) that express the CD8 surface marker efficiently present phagocytosed antigens to CD8(+) T lymphocytes in a process called "crosspresentation," which initiates cytotoxic immune responses. We now show that the small GTPase Rac2 plays a critical role in antigen crosspresentation selectively in this DC subpopulation. In CD8(+) DCs, Rac2 determines the subcellular assembly of the NADPH oxidase complex (NOX2) to phagosomes, whereas in CD8(-) DCs, Rac1 mediates the assembly of NOX2 at the plasma membrane. In the absence of Rac2, the production of reactive oxygen species (ROS) in DC-phagosomes was abolished, the phagosomal pH dropped, and the efficiency of antigen crosspresentation was reduced. We conclude that the activity of Rac1 and 2 control crosspresentation in DC subpopulations through the regulation of phagosomal oxidation and pH.
authors.affiliation: Institut Curie, INSERM U653, Immunité et Cancer, 26 rue d'Ulm, 75248 Paris, Cedex 05, France. ariel.savina@curie.fr
authors.forename: Ariel
authors.initials: A
authors.lastname: Savina
authors.forename: Audrey
authors.initials: A
authors.lastname: Peres
authors.forename: Ignacio
authors.initials: I
authors.lastname: Cebrian
authors.forename: Nuno
authors.initials: N
authors.lastname: Carmo
authors.forename: Catarina
authors.initials: C
authors.lastname: Moita
authors.forename: Nir
authors.initials: N
authors.lastname: Hacohen
authors.forename: Luis F
authors.initials: LF
authors.lastname: Moita
authors.forename: Sebastian
authors.initials: S
authors.lastname: Amigorena