SAA-induced G-CSF secretion in macrophages is not dependent on FPRL1. (A) Effect of PTX on SAA-induced G-CSF secretion. Mouse BMDMs were treated overnight either with PTX at indicted concentrations or with buffer control and then stimulated with SAA for 16 hours. The secreted G-CSF was determined with ELISA. (B) Mouse BMDMs were stimulated with SAA, WKYMVm (W-pep), WRW4 peptide, or SAA after pretreatment with WRW4 for 30 minutes at the indicated concentrations. After 16 hours, secreted G-CSF was determined with ELISA and presented as percentage of change, with maximal G-CSF (446 pg/mL/10⁶ cells) set as 100%. Data are mean plus or minus SEM of 3 experiments, each performed in duplicate. To ensure that PTX, W-pep, and WRW4 were working properly through FPRL1, Fluo-3/AM–labeled mouse bone marrow neutrophils were used to measure the intracellular calcium mobilization with different FPRL1 ligands and antagonists. (C) Cells were pretreated with or without PTX (500 ng/mL, 1 hour) and then stimulated with 0.1 μM SAA. (D) Cells were stimulated with W pep (0.1 μM) or WRW4 (10 μM), and then SAA (0.1 μM). One representative experiment of a total of 3 is shown.