FIGURE 7.

Desialylation differentially alters cellular sensitivity toward galectin-induced PS exposure. A-H, HL60 cells were either incubated with buffer control (A-D) or 100 milliunits of A. ureafaciens neuraminidase (E-H) for 1 h followed by treatment of cells with 20 μm Gal-1, Gal-2, or Gal-3. Cells were washed in 50 mm lactose, stained with annexin-V FITC and propidium iodide (PI), followed by flow cytometric analysis. Cells that were annexin-V-positive and propidium iodide-negative were considered positive for PS exposure. Numbers represent the percent of total cells found in each quadrant. I, HL60 cells were treated with 100 milliunits of A. ureafaciens neuraminidase for 1 h, followed by staining with 10 μg/ml Gal-2 and analysis by flow cytometry. J, quantification of Gal-1, Gal-2, and Gal-3 binding toward HL60 cells following treatment with A. ureafaciens neuraminidase. Bars represent the percent change in cell surface binding when compared with the mean fluorescent intensity of nontreated cells ± S.D. K, quantification of PS exposure (annexin-V⁺/PI^-) on neuraminidase-treated (NT) or untreated cells following treatment with Gal-1, Gal-2, or Gal-3 as outlined in A as mean percentage ± S.D.