PTX treatment facilitates lymphocyte egress and localization in cortical sinuses in Lyve-1 Cre⁺ Sphk-deficient mice. (A–C) Splenocytes were treated with either PTX or OB and cotransferred into recipient hosts. 22 h later, transferred cell numbers were determined in the lymph and LNs of Lyve-1 Cre⁺ Sphk-deficient (Sphk Δ) and control hosts. (A) Flow cytometric analysis of transferred T cells present in the lymph. PTX-treated cells were CFSE labeled. Numbers refer to the percentage of cells in the indicated gates. (B) Frequency of transferred OB (O)- and PTX (P)-treated cells in peripheral LNs (pLN), mesenteric LNs (mLN), and the lymph (Lym). (C) Total numbers of transferred CD4 and CD8 T cells in the lymph of control and Sphk-deficient recipients from the same experiments as in B. In B and C, points indicate data from individual mice, and bars indicate means. (D) Distribution of transferred OB- and PTX-treated cells with respect to LN cortical sinuses. Purified T cells were treated and cotransferred into control or Sphk Δ hosts as in A–C. Sections were stained for LYVE-1 (brown) and transferred T cells (blue). Several transferred cells located within sinuses of the Sphk-deficient recipient are marked by arrows. Data in A–D are representative of at least three experiments with one to two mice per experiment. C, control; Δ, Sphk deficient.