García-Ferreras, RaquelOsuna-Pérez, JesúsRamírez-Santiago, GuillermoMéndez-Pérez, AlmudenaAcosta-Moreno, Andrés MDel Campo, LaraGómez-Sánchez, María JIborra, MartaHerrero-Fernández, BeatrizGonzález-Granado, José MSánchez-Madrid, FranciscoCarrasco, Yolanda RBoya, PatriciaMartínez-Martín, NuriaVeiga, Esteban2023-09-072023-09-072023-07-05EMBO Rep. 2023 Jul 5;24(7):e56131http://hdl.handle.net/20.500.12105/16425In addition to triggering humoral responses, conventional B cells have been described in vitro to cross-present exogenous antigens activating naïve CD8+ T cells. Nevertheless, the way B cells capture these exogenous antigens and the physiological roles of B cell-mediated cross-presentation remain poorly explored. Here, we show that B cells capture bacteria by trans-phagocytosis from previously infected dendritic cells (DC) when they are in close contact. Bacterial encounter "instructs" the B cells to acquire antigen cross-presentation abilities, in a process that involves autophagy. Bacteria-instructed B cells, henceforth referred to as BacB cells, rapidly degrade phagocytosed bacteria, process bacterial antigens and cross-prime naïve CD8+ T cells which differentiate into specific cytotoxic cells that efficiently control bacterial infections. Moreover, a proof-of-concept experiment shows that BacB cells that have captured bacteria expressing tumor antigens could be useful as novel cellular immunotherapies against cancer.engVoRhttp://creativecommons.org/licenses/by-nc-nd/4.0/CD8-Positive T-LymphocytesDendritic CellsAntigen PresentationCross-PrimingAntigens, BacterialAttribution-NonCommercial-NoDerivatives 4.0 Internacional37184882247e5613110.15252/embr.2022561311469-3178EMBO reportsopen access