L-selectin engagement by ligands increased lymphocyte surface expression of CXCR4. (A) PBMCs were incubated with 100 μg/mL fucoidan or sulfatide at 37°C for 1 hour. CXCR4 expression was examined by staining cells with PE-conjugated anti-CXCR4. Means ± SEM of relative expressions (% of control) from 11 experiments are shown. *P < .05, **P < .01 compared to untreated. (B) Time-dependent stimulation of CXCR4 expression (n = 4). ○ indicates control; □, fucoidan; and ▵, sulfatide. (C) Fucoidan and sulfatide did not alter β₂-integrin, CCR5, and CCR7 expression on lymphocytes. PBMCs were incubated with fucoidan or sulfatide each at 100 μg/mL for 1 hour at 37°C. Cell surface expression of β₂ integrin, CCR5, and CCR7 was analyzed by immunofluorescence staining with antibodies IB4, 2D7, and 2H4, respectively. Means ± SEM of relative fluorescence intensity (% of control) from 3 separate experiments are presented. (D) HeLa cells were treated with 100 μg/mL fucoidan or sulfatide at 37°C for 1 hour. CXCR4 expression was examined by anti-CXCR4 and flow cytometry. Representative histograms from 1 of 3 similar experiments are shown. Thick lines indicate anti-CXCR4; thin lines, control IgG.