title: Regulatory T cells promote early influx of CD8+ T cells in the lungs of respiratory syncytial virus-infected mice and diminish immunodominance disparities.
abstract: In addition to regulating autoimmunity and antitumor immunity, CD4(+) CD25(+) FoxP3(+) natural regulatory T (Treg) cells are global regulators of adaptive immune responses. Depletion of these cells with the anti-CD25 antibody PC61 prior to primary respiratory syncytial virus (RSV) infection was partial but had several effects on the RSV-specific CD8(+) response in a hybrid mouse model. Mediastinal lymph node and spleen epitope-specific CD8(+) T-cell responses were enhanced in Treg-cell-depleted mice at all time points following infection, but responses of Treg-cell-depleted lung show a strikingly different pattern than lymphoid organ responses, with an initial delay in the CD8(+) T-cell response. The delay in the CD8(+) T-cell response correlated with a delay both in the early phase of viral clearance and in illness in Treg-cell-depleted mice compared to isotype-treated controls. The lungs of Treg-cell-depleted mice were shown to have increased lung chemokine and cytokine levels 7 days postinfection despite lower CD8(+) T-cell responses. Following the early delay in the lung response, CD8(+) T-cell responses at later infection time points were enhanced and increased the severity of illness in depleted mice. Finally, decreasing regulatory T-cell control of the CD8(+) T-cell response had a greater effect on response of the dominant K(d)-restricted M2 epitope consisting of amino acids 82 to 90 (K(d)M2(82-90)) than on the subdominant D(b)M(187-195) epitope response, indicating that regulatory T cells modulate immunodominance disparities in epitope-specific CD8(+) T-cell responses following primary RSV infection.
authors.affiliation: Viral Pathogenesis Laboratory, Vaccine Research Center, National Institute of Allergy and Infections Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Tracy J
authors.initials: TJ
authors.lastname: Ruckwardt
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Bonaparte
authors.forename: Martha C
authors.initials: MC
authors.lastname: Nason
authors.forename: Barney S
authors.initials: BS
authors.lastname: Graham
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D016207:Cytokines / Q000032:analysis; D005260:Female; D008168:Lung / Q000737:chemistry / Q000276:immunology* / Q000473:pathology / Q000821:virology*; D008198:Lymph Nodes / Q000276:immunology; D008212:Lymphocyte Depletion; D051379:Mice; D018357:Respiratory Syncytial Virus Infections / Q000276:immunology* / Q000473:pathology; D012136:Respiratory Syncytial Viruses / Q000276:immunology; D012720:Severity of Illness Index; D013154:Spleen / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D016207:Cytokines