title: Essential role of lymph nodes in contact hypersensitivity revealed in lymphotoxin-alpha-deficient mice.
abstract: Lymph nodes (LNs) are important sentinal organs, populated by circulating lymphocytes and antigen-bearing cells exiting the tissue beds. Although cellular and humoral immune responses are induced in LNs by antigenic challenge, it is not known if LNs are essential for acquired immunity. We examined immune responses in mice that lack LNs due to genetic deletion of lymphotoxin ligands or in utero blockade of membrane lymphotoxin. We report that LNs are absolutely required for generating contact hypersensitivity, a T cell-dependent cellular immune response induced by epicutaneous hapten. We show that the homing of epidermal Langerhans cells in response to hapten application is specifically directed to LNs, providing a cellular basis for this unique LN function. In contrast, the spleen cannot mediate contact hypersensitivity because antigen-bearing epidermal Langerhans cells do not access splenic white pulp. Finally, we formally demonstrate that LNs provide a unique environment essential for generating this acquired immune response by reversing the LN defect in lymphotoxin-alpha(-/)- mice, thereby restoring the capacity for contact hypersensitivity.
authors.affiliation: Department of Immunology and Inflammation, Biogen, Incorporated, 14 Cambridge Center, Cambridge, MA 02142, USA. paul_rennert@biogen.com
authors.forename: P D
authors.initials: PD
authors.lastname: Rennert
authors.forename: P S
authors.initials: PS
authors.lastname: Hochman
authors.forename: R A
authors.initials: RA
authors.lastname: Flavell
authors.forename: D D
authors.initials: DD
authors.lastname: Chaplin
authors.forename: S
authors.initials: S
authors.lastname: Jayaraman
authors.forename: J L
authors.initials: JL
authors.lastname: Browning
authors.forename: Y X
authors.initials: YX
authors.lastname: Fu
mesh_terms: D000818:Animals; D002465:Cell Movement; D003713:Dendritic Cells / Q000502:physiology; D003877:Dermatitis, Contact / Q000209:etiology*; D005260:Female; D007801:Langerhans Cells / Q000502:physiology; D008198:Lymph Nodes / Q000502:physiology*; D008233:Lymphotoxin-alpha / Q000502:physiology*; D053308:Lymphotoxin-beta; D008565:Membrane Proteins / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H
chemical_list: C505887:Ltb protein, mouse; D008233:Lymphotoxin-alpha; D053308:Lymphotoxin-beta; D008565:Membrane Proteins