CD8⁺ αβ T cells can mediate late airway responses and airway eosinophilia in rats

Background

The function of CD8⁺ T-cell subsets in mediating late allergic responses is incompletely understood.

Objective

We sought to test the hypothesis that CD8⁺ αβ T cells are proinflammatory in the airways in vivo by using a well-characterized animal model and the technique of adoptive transfer

Methods

Brown Norway rats were administered CD8⁺ αβ T cells (10⁶) intraperitoneally purified from lymph node cells of either naive or ovalbumin (OVA)–sensitized rats and were challenged with aerosolized OVA 2 days later. Control rats were sensitized to 100 μg of OVA in Al(OH)₃ subcutaneously or sham sensitized to saline and were OVA challenged 2 weeks later.

Results

The OVA-sensitized and OVA-challenged group and the recipients of OVA-primed CD8⁺ αβ T cells had significant late airway responses calculated from lung resistance measured for an 8-hour period after challenge compared with the naive CD8⁺ αβ T cell–transferred group and the sham-sensitized control group. The number of eosinophils in bronchoalveolar lavage fluid increased in the OVA-sensitized group and the OVA-primed CD8⁺ αβ T-cell recipients compared with numbers in the naive CD8⁺ αβ T-cell recipients and the sham-sensitized control group. IL-4 and IL-5 cytokine mRNA expression in bronchoalveolar lavage fluid increased in the OVA-sensitized group and the OVA-primed CD8⁺ αβ T-cell recipients compared with that in the sham-sensitized group.

Conclusion

We conclude that antigen-primed CD8⁺ αβ T cells might have a proinflammatory role in allergen-driven airway responses in the rat.

Key words: Lung, allergy, inflammation, T lymphocytes, cytokines

Abbreviations used: AHR, Airway hyperresponsiveness, BAL, Bronchoalveolar lavage, BN, Brown Norway, EAR, Early airway response, LAR, Late airway response, MACS, Magnetic cell sorting, MBP, Major basic protein, OVA, Ovalbumin, R_L, Lung resistance, TCR, T-cell receptor