Figure 3.

Location of S1P₁ positive B lymphocytes within the lymph node follicle. (A-B) B220, CD3, and S1P₁ immunostaining. Lymph node thin sections immunostained as indicated. Rabbit IgG is the control antibody (A) for S1P₁ immunostaining (B). Magnified images of the white boxed regions are shown in the lower panels, the left two from deep in the follicle and the right two from the T-B border. (C) B220 and LYVE-1 immunostaining. Lymph node thin section immunostained as indicated. (D) S1P₁ and LYVE-1 immunostaining around HEV and lymphatic. The left panel shows S1P₁ immunostaining in the region outlined by the white box from part C. Yellow arrows indicate punctate staining of S1P₁. The right panel shows S1P₁ and LYVE-1 staining of the same region. (E) S1P₁ immunostaining of cells in the lymphatics. Region outlined by white box in part D contains cells within lymphatic lumen. Upper panel shows LYVE- 1 (green) versus S1P1 (red) and lower panel shows LYVE-1 (green) versus B220 (white). (F-G) S1P₁ immunostaining of lymph node sections from FTY720 treated and control mice. Mice were treated with FTY720 (1 μg/gm body weight for 18 hours or not). Lymph node sections (7 μM) were stained with antibodies against B220 (white), LYVE-1 (green) and S1P₁ (red). White box areas are magnified and S1P₁ staining is shown. Lymphatic endothelium staining is indicated (arrows).