Distribution of E-selectin tethering activity among leukocyte gangliosides. The monosialoglycosphingolipids from human leukocytes were resolved by HPLC (Figure 4) and quantified based on A₂₁₅ (). Total E-selectin tethering activity in each fraction was calculated by dividing the amount of ganglioside in that fraction by the minimal amount required to support significant E-selectin–mediated tethering. The resulting tethering activity in each fraction is plotted as a percentage of the total GSL tethering activity (■). Fucosylated species detected by MALDI-TOF MS of the resolved fractions are designated above the chromatogram ( indicates minor species), with structure abbreviations (n/m) as defined in Figure 1 legend. Only the trailing fractions of the HPLC run are shown, representing all of the E-selectin tethering activity and approximately 10% of the total leukocyte monosialo GSLs.