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Keywords:

  • Adhesion molecules;
  • Allergy;
  • CCL25;
  • Chemokines;
  • T cells

Herein, we provide evidence that during allergic inflammation, CCL25 induces the selec-tive migration of IL-17+ γδ T cells mediated by α4β7 integrin. Intrapleural injection of CCL25 into ovalbumin (OVA)-immunized C57BL/6 mice triggered the accumulation of γδ T lymphocytes expressing CCR9 (CCL25 receptor) and α4β7 integrin in the pleura, but failed to attract αβ T lymphocytes. CCL25 attracted CCR6+ γδ T cells producing IL-17 (but not IFN-γ or IL-4). OVA challenge triggered increased production of CCL25 followed by the accumulation of CCR9+, α4β7+, and CCR6+/IL-17+ γδ T cells into the pleural cavities of OVA-immunized mice, which was inhibited by the in vivo neutralization of CCL25. The in vivo blockade of α4β7 integrin also inhibited the migration of IL-17+ γδ T lymphocytes (but not of αβ T lymphocytes) into mouse pleura after OVA challenge, suggesting that the CCL25/α4β7 integrin pathway is selective for γδ T cells. In addition, α4β7 integrin blockade impaired the in vitro transmigration of γδ T cells across endothelium (which expresses α4β7 ligands VCAM-1 and MadCAM-1), which was induced by CCL25 and by cell-free pleural washes recovered from OVA-challenged mice. Our results reveal that during an allergic reaction, CCL25 drives IL-17+ γδ T-cell mobilization to inflamed tissue via α4β7 integrin and modulates IL-17 levels.