Neutrophil expression of sLe^x and PSGL-1. The surface expression of sLe^x (A and C) and PSGL-1 (B and D) on neutrophils from a normal donor (A and B) and the patient (C and D) was determined by FACS analysis. Filled and unfilled tracings represent, respectively, the background staining and staining for the targeted protein. For the normal donor and the patient comparable levels of expression of sLe^x and PSGL-1 were noted.