Cruz-Adalia, A.; Ramirez-Santiago, G.; Calabia-Linares, C.; Torres-Torresano, M.; Feo, L.; Galan-Diez, M.; Fernandez-Ruiz, E.; Pereiro, E.; Guttmann, P.; Chiappi, M.; Schneider, G.; Lopez Carrascosa, J.; Javier Chichon, F.; Martinez del Hoyo, G.; Sanchez-Madrid, F.; Veiga, E.: T Cells Kill Bacteria Captured by Transinfection from Dendritic Cells and Confer Protection in Mice. Cell Host & Microbe 15 (2014), p. 611-622

During infections, dendritic cells (DCs) phagocytose, process and present bacterial-antigens to the T lymphocytes, thus triggering the adaptive immunity. In vivo, bacteria can be found inside antigen presenting cells (APCs) and lymphocytes, however, how bacteria invade T cells remains unknown. Here we show that T cells take up bacteria from infected DCs in a process remarkably enhanced by antigen recognition herein called trans-infection. Strikingly, trans-infected T cells efficiently eliminate the bacteria acquired from the infected DCs within the first hours after trans-infection. Moreover, trans-infected T cells produced high levels of pro-inflammatory cytokines and were able to protect mice from bacterial challenge after adoptive transfer. Our data, therefore, show that T lymphocytes resemble to cells of the innate immune system in the sense that they are able to engulf and kill bacteria demonstrating novel and unexpected roles for T lymphocytes during bacterial clearance.