title: B7 costimulation is critical for antibody class switching and CD8(+) cytotoxic T-lymphocyte generation in the host response to vesicular stomatitis virus.
abstract: Antibody and cytotoxic T-lymphocyte (CTL) responses have critical roles in eliminating many viral infections. In addition to stimulation of the T-cell receptor, T cells require costimulatory signals to respond optimally. We evaluated the role of B7 costimulatory molecules (B7-1 and B7-2) in the immune response to viral infection using vesicular stomatitis virus (VSV) and mice lacking either B7-1 or B7-2 or both molecules. Mice lacking both B7-1 and B7-2 had essentially no anti-VSV immunoglobulin G1 (IgG1) response, decreased IgG2a responses, and normal IgM responses, while mice lacking either B7-1 or B7-2 had unaltered anti-VSV antibody responses compared to wild-type mice. Depletion of CD4(+) cells further reduced the IgG2a response in mice lacking both B7 molecules, suggesting that CD4(-) cells may supply help for IgG2a in the absence of B7 costimulation. The absence of both B7 molecules profoundly reduced generation of both primary and secondary VSV-specific class I major histocompatibility complex (MHC)-restricted CTL, whereas VSV-specific CTL responses in mice lacking either B7-1 or B7-2 were similar to those of wild-type animals. Class I MHC-restricted CTL in wild-type mice were not dependent on CD4(+) cells, suggesting that the failure of CTL in the absence of B7s is due to a lack of B7 costimulation directly to the CD8(+) CTL. These data demonstrate that B7-1 and B7-2 have critical, overlapping functions in the antibody and CTL responses to this viral infection.
authors.affiliation: Departments of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. ajmcadam@bics.bwh.harvard.edu
authors.forename: A J
authors.initials: AJ
authors.lastname: McAdam
authors.forename: E A
authors.initials: EA
authors.lastname: Farkash
authors.forename: B E
authors.initials: BE
authors.lastname: Gewurz
authors.forename: A H
authors.initials: AH
authors.lastname: Sharpe
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D015703:Antigens, CD / Q000235:genetics / Q000502:physiology*; D018122:B7-1 Antigen / Q000235:genetics / Q000502:physiology*; D051940:B7-2 Antigen; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014721:Vesicular stomatitis Indiana virus / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; C497965:Cd86 protein, mouse; D008562:Membrane Glycoproteins