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Effect of CD8 + T‐cell depletion on bronchial hyper‐responsiveness and inflammation in sensitized and allergen‐exposed Brown–Norway rats
Author(s) -
Huang Tj,
MacAry Pa,
Kemeny Dm,
Kian Fan Chung
Publication year - 1999
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.1999.00699.x
Subject(s) - immunology , inflammation , allergen , asthma , biology , medicine , allergy
We examined the role of CD8 + T cells in a Brown–Norway rat model of asthma, using a monoclonal antibody to deplete CD8 + T cells. Ovalbumin (OA)‐sensitized animals were given anti‐CD8 antibody (0·5 mg/rat) intravenously 1 week prior to exposure to 1% OA aerosol and were studied 18–24 hr after aerosol exposure. Following administration of anti‐CD8 antibody, CD8 + cells were reduced to <1% of total lymphocytes in whole blood and in spleen. In sensitized animals, OA exposure induced bronchial hyper‐responsiveness (BHR), accumulation of eosinophils, lymphocytes and neutrophils in bronchoalveolar lavage (BAL) fluid, and also an increase in tissue eosinophils and CD2 + , CD4 + and CD8 + T cells in airways. Anti‐CD8 antibody caused a further increase in allergen‐induced BHR ( P <0·03, compared with sham‐treated animals), together with a significant increase in eosinophil number in BAL fluid ( P <0·05). While CD2 + and CD4 + T cells in airways were not affected by anti‐CD8 treatment, the level of CD8 + T cells was significantly reduced in sensitized, saline‐exposed animals ( P <0·04, compared with sham‐treated rats), and sensitized and OA‐challenged rats ( P <0·002, compared with sham‐treated rats). Using reverse transcription–polymerase chain reaction, an increase of T helper (Th)2 cytokine [interleukin (IL)‐4 and IL‐5], and also of Th1 cytokine [interferon‐γ (IFN‐γ) and IL‐2], mRNA in the lung of sensitized and OA‐exposed animals was found; after CD8 + T‐cell depletion, Th1 cytokine expression was significantly reduced ( P <0·02), while Th2 cytokine expression was unchanged. CD8 + T cells have a protective role in allergen‐induced BHR and eosinophilic inflammation, probably through activation of the Th1 cytokine response.