Resident CD8 + T cells suppress CD4 + T cell–dependent late allergic airway responses

• Published in: Journal of allergy and clinical immunology 2005-03, Vol.115 (3), p.521-526
• Main Authors: Isogai, Susumu, Jedrzkiewicz, Sean, Taha, Rame, Hamid, Qutayba, Martin, James G.
• Format: Article
• Language: English
• Subjects: Adoptive Transfer; Animals; Bronchoalveolar Lavage Fluid - cytology; Bronchoalveolar Lavage Fluid - immunology; Brown Norway rat; CD4 + T cells; CD4-Positive T-Lymphocytes - immunology; CD8 + T cells; CD8-Positive T-Lymphocytes - immunology; Cytokines; eosinophils; Flow Cytometry; Immune system; Immunohistochemistry; In Situ Hybridization; Interferon-gamma - immunology; Interleukin-4 - immunology; Interleukin-5 - immunology; late allergic responses; Lymphocytes; Ovalbumin - immunology; Rats; Respiratory Hypersensitivity - immunology; RNA, Messenger; Rodents; T cell receptors; T H2 cytokines
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2004.11.036

The role of CD8 + T cells in the immune response to airway challenge with an allergen is poorly understood. The aim of this study was to test the hypothesis that resident naive CD8 + T cells modulate the magnitude of CD4 + T cell–dependent allergic airway responses. Cervical lymph node CD4 + T cells (2 × 10 6) were harvested from ovalbumin (OVA)– or sham-sensitized rats and injected intraperitoneally into naive Brown Norway recipients. The recipients were treated with a CD8α mAb (OX-8) to deplete the resident CD8 + T cells (n = 12) or mouse ascites (n = 12). Two days after adoptive transfer, the recipient animals were OVA challenged, lung resistance was measured for 8 hours, and bronchoalveolar lavage (BAL) was performed. After OVA challenge, primed CD4-transferred CD8-depleted rats had larger early airway responses and late airway responses compared with primed CD4-transferred CD8-nondepleted rats (early airway responses: 158.6% ± 19.2% vs 115.7% ± 5.9%, P < .05; late airway responses: 8.5% ± 1.7% vs 4.4% ± 0.9%, P < .05). BAL eosinophilia was also greater (4.67% ± 0.45% vs 2.34 ± 0.26%, P < .01). The cells in BAL fluid expressing IL-4 mRNA were not significantly changed by CD8 depletion, but IL-5 mRNA + cells were higher in number, and IFN-γ mRNA + cells were fewer in the CD8-depleted group. Resident CD8 + T cells downregulate the late allergic response and airway inflammation evoked by CD4 + T-cell transfers in Brown Norway rats. This downregulation does not require antigen priming.