title: T cells home to the thymus and control infection.
abstract: The thymus is a target of multiple pathogens. How the immune system responds to thymic infection is largely unknown. Despite being considered an immune-privileged organ, we detect a mycobacteria-specific T cell response in the thymus following dissemination of Mycobacterium avium or Mycobacterium tuberculosis. This response includes proinflammatory cytokine production by mycobacteria-specific CD4(+) and CD8(+) T cells, which stimulates infected cells and controls bacterial growth in the thymus. Importantly, the responding T cells are mature peripheral T cells that recirculate back to the thymus. The recruitment of these cells is associated with an increased expression of Th1 chemokines and an enrichment of CXCR3(+) mycobacteria-specific T cells in the thymus. Finally, we demonstrate it is the mature T cells that home to the thymus that most efficiently control mycobacterial infection. Although the presence of mature T cells in the thymus has been recognized for some time, to our knowledge, these data are the first to show that T cell recirculation from the periphery to the thymus is a mechanism that allows the immune system to respond to thymic infection. Maintaining a functional thymic environment is essential to maintain T cell differentiation and prevent the emergence of central tolerance to the invading pathogens.
authors: Life and Health Sciences Research Institute, School of Health Sciences, University of Minho, 4710-057 Braga, Portugal.
authors: Claudia
authors: C
authors: Nobrega
authors: Cláudio
authors: C
authors: Nunes-Alves
authors: Bruno
authors: B
authors: Cerqueira-Rodrigues
authors: Susana
authors: S
authors: Roque
authors: Palmira
authors: P
authors: Barreira-Silva
authors: Samuel M
authors: SM
authors: Behar
authors: Margarida
authors: M
authors: Correia-Neves
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000276:immunology*; D054357:Chemokine CXCL10 / Q000096:biosynthesis; D054370:Chemokine CXCL9 / Q000096:biosynthesis; D007113:Immunity, Innate; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009162:Mycobacterium avium / Q000276:immunology; D009169:Mycobacterium tuberculosis / Q000276:immunology; D054367:Receptors, CXCR3 / Q000096:biosynthesis; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology; D013950:Thymus Gland / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology; D014376:Tuberculosis / Q000276:immunology / Q000517:prevention & control
chemical_list: D054357:Chemokine CXCL10; D054370:Chemokine CXCL9; C485433:Cxcl10 protein, mouse; C485969:Cxcl9 protein, mouse; C515188:Cxcr3 protein, mouse; D054367:Receptors, CXCR3