title: T-cell-independent responses to Borrelia burgdorferi are critical for protective immunity and resolution of lyme disease.
abstract: The humoral immune response to Borrelia burgdorferi during persistent infection is critical to both protective and disease-resolving immunity. This study examined the role of B cells in the absence of T cells during these events, using mice with selected immune dysfunctions. At 6 weeks postinfection, an interval at which arthritis resolves in immunocompetent mice, arthritis severity was equivalent among immunocompetent mice, alphabeta(+)-T-cell-deficient mice, and mice lacking both alphabeta(+) and gammadelta(+) T cells. Arthritis severity was worse in SCID mice, which lack T and B lymphocytes. Carditis regressed in immunocompetent mice and those lacking both alphabeta(+) and gammadelta(+) T cells but remained active in mice lacking only alphabeta(+) T cells and in SCID mice. Mice lacking only alphabeta(+) T cells and those lacking both alphabeta(+) and gammadelta(+) T cells generated immunoglobulin M (IgM) and IgG3 B. burgdorferi-reactive antibodies. Sera from infected immunocompetent mice, mice lacking only alphabeta(+) T cells, and mice lacking both alphabeta(+) and gammadelta(+) T cells passively protected naive mice against challenge inoculation with B. burgdorferi. However, only sera from infected immunocompetent mice, but not sera from infected T-cell-deficient mice, were able to resolve arthritis when passively transferred to actively infected SCID mice. These data demonstrate that B-cell activation during a T-cell-independent response may be critical for resolution of arthritis and carditis and that protective antibodies are generated during this response.
authors.affiliation: Center for Comparative Medicine, University of California, Davis, California 95616, USA. mdmckisis@ucdavis.edu
authors.forename: M D
authors.initials: MD
authors.lastname: McKisic
authors.forename: S W
authors.initials: SW
authors.lastname: Barthold
mesh_terms: D000818:Animals; D000955:Antigens, T-Independent / Q000276:immunology*; D007106:Immune Sera / Q000276:immunology; D007116:Immunization, Passive; D015151:Immunoblotting; D017578:Immunoglobulin Class Switching; D016130:Immunophenotyping; D008193:Lyme Disease / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D018345:Mice, Knockout; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000502:physiology; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D000955:Antigens, T-Independent; D007106:Immune Sera; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta