- Chen, Kevin;
- De Giovanni, Marco;
- Xu, Ying;
- An, Jinping;
- Kirthivasan, Nikhita;
- Lu, Erick;
- Jiang, Kan;
- Brooks, Stephen;
- Ranucci, Serena;
- Yang, Jiuling;
- Kanameishi, Shuto;
- Kabashima, Kenji;
- Brulois, Kevin;
- Bscheider, Michael;
- Butcher, Eugene;
- Cyster, Jason
Sustained lymphocyte migration from blood into lymph nodes (LNs) is important for immune responses. The CC-chemokine receptor-7 (CCR7) ligand CCL21 is required for LN entry but is downregulated during inflammation, and it has been unclear how recruitment is maintained. Here, we show that the oxysterol biosynthetic enzyme cholesterol-25-hydroxylase (Ch25h) is upregulated in LN high endothelial venules during viral infection. Lymphocytes become dependent on oxysterols, generated through a transcellular endothelial-fibroblast metabolic pathway, and the receptor EBI2 for inflamed LN entry. Additionally, Langerhans cells are an oxysterol source. Ch25h is also expressed in inflamed peripheral endothelium, and EBI2 mediates B cell recruitment in a tumor model. Finally, we demonstrate that LN CCL19 is critical in lymphocyte recruitment during inflammation. Thus, our work explains how naive precursor trafficking is sustained in responding LNs, identifies a role for oxysterols in cell recruitment into inflamed tissues, and establishes a logic for the CCR7 two-ligand system.