Effect of rPSGL-Ig on the murine chemokine KC.
(A-C) Fluorescent KC binds to rPSGL-Ig–coated beads. Differently coated nonfluorescent beads were incubated with FITC-KC, and association was determined by means of flow cytometry. In panel A, open histogram indicates nonfluorescent rPSGL-Ig–coated beads; filled histogram indicates rPSGL-Ig–coated beads incubated with FITC-KC. In panel B, open histogram indicates nonfluorescent low-affinity rPSGL-Ig–coated beads; filled histogram indicates low-affinity rPSGL-Ig–coated beads incubated with FITC-KC. In panel C, open histogram indicates FITC-KC incubated with rPSGL-Ig prior to incubation with rPSGL-Ig–coated beads; filled histogram indicates FITC-KC incubated with low-affinity rPSGL-Ig prior to incubation with rPSGL-Ig–coated beads. (D) Migration of murine neutrophils toward KC is inhibited by rPSGL-Ig. Purified mouse neutrophils were incubated with vehicle (open bars), CD4-Ig (hatched bars), low-affinity rPSGL-Ig (checked bars), or rPSGL-Ig (filled bars) (all at 10 μg/mL) and allowed to migrate over ChemoTx chambers in response to the chemokine KC. The percentage of migration was calculated by expressing the number of migrated neutrophils as a percentage of the total number added to the chamber. Results are presented as means ± SEMs of 5 or 6 experiments. **Indicates a statistically significant difference from vehicle, P < .01. (E) Concentration-dependent inhibition of murine neutrophil migration by rPSGL-Ig. Purified mouse neutrophils were incubated with different concentrations of rPSGL-Ig prior to migration in response to 10−6 M KC. Results are presented as the percentage of control migration, where 100% is the percentage induced by 10−6 M KC with nonspecific migration toward vehicle (RPMI) subtracted. Means ± SEMs of n = 4 experiments are shown.
