Airway epithelial cell-derived insulin-like growth factor-1 triggers skewed CD8(+) T cell polarization

Skewed CD8(+) T cell responses are important in airway inflammation. This study investigates the role of the airway epithelial cell-derived insulin-like growth factor 1 (IGF1) in contributing to CD8(+) T cell polarization. Expression of IGF1 in the airway epithelial cell line, RPMI2650 cells, was assessed by quantitative real time RT-PCR and Western blotting. The role of IGF1 in regulating CD8(+) T cell activation was observed by coculture of mite allergen-primed RPMI2650 cells and naïve CD8(+) T cells. CD8(+) T cell polarization was assessed by the carboxyfluorescein succinimidyl ester-dilution assay and the determination of cytotoxic cytokine levels in the culture medium. Exposure to mite allergen, Der p1, increased the expression of IGF1 by RPMI2650 cells. The epithelial cell-derived IGF1 prevented the activation-induced cell death by inducing the p53 gene hypermethylation. Mite allergen-primed RPMI2650 cells induced an antigen-specific CD8(+) T cell polarization. We conclude that mite allergens induce airway epithelial cell line, RPMI2650 cells, to produce IGF1; the latter contributes to antigen-specific CD8(+) T cell polarization.