Effect of L-selectin stimulation and SDF-1 on lymphocyte adhesion to the endothelium. Chromium-labeled T lymphocytes were added to confluent monolayers of HUVECs in 96-well plates for 1 hour at 37°C. Fucoidan, anti-L-selectin cross-linking, and SDF-1 either alone or in combinations were used for stimulation. Nonadherent cells were removed by repeated washing. The adherent cells were lysed by 1 N NaOH and radioactivity was measured by gamma counting. (A) L-selectin and SDF-1–induced lymphocyte adhesion to endothelial cells was blocked by anti-LFA-1 but not by anti-VLA-4. (B) Tyrosine kinase inhibitors and PTX inhibited lymphocyte adhesion to endothelial cells. *P ≤ .01 compared with medium alone (selected pairwise comparisons selected a priori).