Sphingosine-1-phosphate (S1P) or supernatant of C5a-stimulated neutrophils upregulated CD88 expression on neutrophils and S1P receptor antagonist reduced C5a-induced neutrophil migration. (A) CD88 expression increased on neutrophils after S1P or supernatant of C5a-stimulated neutrophil engagement in neutrophils. Neutrophils were stimulated with S1P 500 nmol/L, supernatant of C5a-stimulated neutrophils or buffer control for 30 minutes. The expression of CD88 was determined by FACS. A representative example of five independent experiments is shown. (B) Isolated neutrophils were pre-incubated with S1P receptor antagonist at 50 nM and loaded into the upper chamber. After the upper chamber neutrophil co-incubation with C5a 100 ng/ml in the lower chamber, the migration was assayed through counting the number of migrated neutrophils using FACS. Results are presented as the percentage of migrated neutrophils after C5a induced or pre-incubated with S1P receptor antagonist compared with the blank. A representative example of three independent experiments is shown.