Introduction: Sphingosine 1-phospate (S1P) receptor 1 (S1PR1) drives T cell migration from thymus into blood, and lymph nodes (LN) into efferent lymphatics. Whether S1PR1 and S1PR4 expressed by T cells, regulate migration from tissues into draining LN (dLN) is unknown. We hypothesized that T cells use different S1PRs to traffic from tissues into draining LN through afferent lymphatics.

Methods: CD4 T cells were adoptively transferred into mice, and migration to afferent lymphatics and dLN measured. Mouse and human primary lymphatic endothelial cells (LEC), blood endothelial cell (BEC), and LEC line were used to assess migration, chemokine signals, adhesion molecules and S1PR function in vitro. Specific pharmacologic and genetic S1PR blockade was employed in vitro and in vivo.

Results:LEC, but not BEC, selectively promoted human and murine CD4 T cell migration toward S1P, but not other chemokines. An S1P gradient was formed around the afferent lymphatics; anti-S1P treatment inhibited CD4 T cell migration in vitro and in vivo; and CD4 T cells failed to home to LN of Sphk1^-/- and Sphk2^-/- recipients, which lacked lymphatic S1P expression. CD4 T cell migration toward S1P not CCL19 was blocked by treatment of T cells with S1PR1 or S1PR4 antagonists. Similarly, S1PR1^-/- or S1PR4^-/- CD4 T cells failed to migrate toward S1P not CCL19 in vitro, and into afferent lymphatics and LN in vivo. Pharmacologic and genetic receptor blockade inhibited migration both in vitro and in vivo. In contrast, overexpression of S1PR1 in S1PR1-Tg or S5A transgenic T cells promoted CD4 T cell migration toward S1P in vitro and enhanced homing into dLN through afferent lymphatics in vivo. Compared to CCL19 driven migration, S1P driven transendothelial migration was more dependent on transcellular rather than paracellular trafficking. S1PR1 and S1PR4 regulated CD4 T cell migration to, but did not change CD4 T cell localization within, LNs.

Conclusions: S1P engages T cells and LEC to promote migration. CD4 T cells use S1PR1 and S1PR4 to regulate migration into afferent lymphatics and LNs. These results demonstrate unique roles for S1P and S1PRs in regulating T cell migration from tissues into LN, and that distinct receptors and mechanisms are used compared to thymic or efferent lymphatic migration. These findings suggest new and specific drug targets for regulating lymphatic migration in immunity and tolerance.

CITATION INFORMATION: Xiong Y., Piao W., Brinkman C., Li L., Kulinski J., Olivera A., Cartier A., Hla T., Schwab S., Hippen K., Blazar B., Bromberg J. CD4 T Cells Require Both S1PR1 and S1PR4 for Afferent Lymphatic Migration Am J Transplant. 2017;17 (suppl 3).

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