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(+) up 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(+) up 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 mug 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(+) up T cells had significant late airway responses calculated from lung resistance measured for an 8-hour period after challenge compared with the naive CD8(+) up 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(+) up T-cell recipients compared with numbers in the naive CD8(+) up T-cell recipients and the shamsensitized 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(+) up T-cell recipients compared with that in the sham-sensitized group. Conclusion: We conclude that antigen-primed CD8(+) up T cells might have a proinflammatory role in allergen-driven airway responses in the rat.