This was confirmed by the observation that α-GalCer presentation to the DN32.D3 NKT cell clone occurs mainly in the lung and to a lesser extent in the lung-draining lymph node up to 5 days after intranasal administration. However, it is unclear as to how NKT cells and DCs are activated in more distal tissues, such as the

spleen and liver, after a primary intranasal immunization with α-GalCer. It is possible that either activated DCs and/or activated Ivacaftor NKT cells migrate from the lung after stimulation with α-GalCer, or alternatively the cytokine milieu resulting from NKT cell stimulation with α-GalCer may induce activation of these cell types in other tissues. In this regard it has been reported that a decrease in NKT cell populations in the liver

coincided with an increase in the blood NKT cell levels after intraperitoneal immunization with α-GalCer, suggesting potential trafficking of NKT cells 16. It has been observed that multiple find more administrations of DCs pulsed ex vivo with α-GalCer, as opposed to free α-GalCer, do not induce NKT cell anergy 5, 8. On the other hand, it has also been shown that injection of B cells pulsed ex vivo with α-GalCer does induce NKT cell anergy 5, 17. Here we have shown that after intranasal administration, CD11c+ cells, not B220+ cells, more efficiently present α-GalCer in the lung, suggesting that the intranasal route of immunization preferentially targets α-GalCer presentation to DCs. Interestingly,

Hermans et al. 18 showed that presentation of both α-GalCer and peptide antigen by the same DC was required for the strong activation C59 solubility dmso of antigen-specific T-cell responses. Futhermore, Ko et al. 14 showed that the responding DC-presenting antigen in the lung-draining LNs also expresses a CD8α− phenotype. This suggests that the DCs presenting α-GalCer in the lung should show a similar phenotype, which would be intriguing to pursue in the future. In addition to the potential influence of the phenotype of cells presenting α-GalCer to induce NKT cell anergy, recently it has been reported that expression levels of the cell surface marker PD-1 on NKT cells may also be an important factor for anergy induction. In T cells, higher levels of PD-1 expression were observed to be associated with functional exhaustion resulting from interactions with either of its ligands, PD-L1 or PD-L2, which are both commonly expressed on APCs including B cells, DCs, and macrophages 19–21. It has also been observed that PD-1 expression is up-regulated on the ‘exhausted’ CD8+ T cells in HIV-infected patients and blocking of the PD-1/PD-L1 interaction could rescue the exhausted T cells in terms of restoring functional properties 22, 23.