Characterization of BLyS secretion by G-CSF–treated neutrophils stimulated with proinflammatory mediators. (A) Neutrophils were incubated with doses of G-CSF ranging from 10 to 1000 U/mL for 20 hours before the addition of CXCL8, TNF-α, or IC. After an additional 4 hours, cell-free supernatants and the corresponding cell pellets were harvested for determination of antigenic BLyS. Mean values of the total production of BLyS (depicted as cell associated and released) are shown. The experiment depicted in this figure is representative of 2. (B) Neutrophils were preincubated with 100 U/mL G-CSF for 20 hours before the addition of CXCL8, C5a, and TNF-α at the doses indicated. After an additional 4 hours, cell-free supernatants were harvested for determination of antigenic BLyS. Mean values of released BLyS are shown. The experiment depicted in this figure is representative of 3.