It is noteworthy that the participation of CCL20 in IL-17+ γδ T-cell migration during allergy cannot be ruled out. The fact that CCL20 neutralization slightly diminished IL-17+ γδ T-cell chemotaxis toward OPW suggests that CCL20/CCR6

and CCL25/CCR9 might cooperate for their attraction to the allergic site. Even though the CCR9/α4β7 expression determines a phenotype of intestinal mucosa population [[18]], we detected the presence of CCR9+/α4β7+ lymphocytes in the pleura during the allergic response. It has been demonstrated that CCL25 induces T-cell adhesion via α4β7 integrin [[17]] and preferentially induces the migration of α4β7+ T cells via CCR9 [[36]]; even though the mechanisms involved in this phenomenon remain to be elucidated. γδ T cells express several Selleckchem MK1775 integrins, such α4β1 and α4β7, which are known to be important for the adhesion to the endothelium and transmigration into inflamed tissue [[22, 23, 37-39]]. Indeed, selective blocking mAbs against α4β1 integrin inhibited human γδ T-lymphocyte adhesion to cytokine-activated check details endothelial cells [[24]]. Moreover, CCL25 has been shown to induce T lymphocyte adhesion via the interaction of α4β7 and α4β1 integrins to MadCAM-1 and VCAM-1, respectively [[16, 17]]. These data corroborate

our findings that CCL25 induced the transmigration of γδ T lymphocytes through endothelial cells, via the interaction of α4β7 integrin to MadCAM-1/VCAM-1. During allergy, the expression of VCAM-1 (but not ICAM-1) by mouse endothelium has been shown to be upregulated [[40]]. In addition, the pentoxifylline in vitro stimulation of HUVECs by the Th2 cyto-kine IL-4 also induced the expression of VCAM-1, failing to alter ICAM-1 expression [[41]], which is in accordance with our observations that IL-4 triggered increased expression

of VCAM-1 and MadCAM-1 on mouse endothelial cells, but not of ICAM-1 (not shown). Previous reports have shown the importance of the α4 integrin chain for the in vivo migration of T lymphocytes that are shown to preferentially migrate via α4 integrin/VCAM-1 pathway rather than via αLβ2 or ICAM-1 [[40, 42]]. However, no data specifically concerned the role of α4β7 integrin on γδ T-lymphocyte migration during an allergic response. Our results demonstrate the relevance of α4β7 integrin for γδ T-cell migration during an allergic reaction, which was reinforced by the fact that the ex vivo blockade of α4 chain impaired the migration of adoptively transferred CFSE+ γδ T lymphocytes into the allergic site. Moreover, we observed that αLβ2 blockade failed to inhibit γδ T lymphocyte in vitro transmigration toward OPW (not shown). It is also noteworthy that OVA immunization induced a sevenfold increase on the numbers of γδ T cells expressing α4β7 integrin in the spleen (not shown).