The synthetic chemoattractant Trp-Lys-Tyr-Met-Val-DMet activates neutrophils preferentially through the lipoxin A(4) receptor

A D-methionine-containing peptide, Trp-Lys-Tyr-Met-Val-D-Met-NH2 (WKYMVm), featuring a unique receptor specificity was investigated with respect to it s ability to activate neutrophil effector functions. The peptide was found to be more potent than the N-formylated peptide N-formyl-Met-Leu-Phe (fMLF) at inducing neutrophil chemotaxis, mobilization of neutrophil complement r eceptor 3 (CR3), and activation of the neutrophil NADPH-oxidase. The fact t hat binding of fML[H-3]F was inhibited by both fMLF and WKYMVm suggests tha t N-formyl peptide receptor (FPR) is shared by these peptides. However, the neutrophil response induced by the WKYMVm peptide was insensitive to the f MLF antagonists, cyclosporin H, and Boc-FLFLF that specifically block the f unction of the FPR. These results suggest that even though WKYMVm may bind FPR the cells are activated preferentially through a receptor distinct from the FPR. Using transfected HL-60 cells expressing either the FPR or its ne utrophil homologue FPRL1, also referred to as LXA(4)R because it has been s hown to bind lipoxin A(4), we show that WKYMVm is about 300-fold more activ e at mobilizing intracellular calcium through FPRL1 than through FPR, The W KYMVm activates FPRL1-expressing cells in a cyclosporin H-independent manne r with an EC50 of around 75 pmol/L, whereas it activates FPR-expressing cel ls with an EC50 of around 25 nmol/L. The observation that exudated cells ar e primed in their response to WKYMVm suggests that FPRL1/ LXA4R like FPR is stored in mobilizable organelles. (C) 2000 by The American Society of Hema tology.