2 FOR-MET-LEU-PHE-OME ANALOGS TRIGGER SELECTIVE NEUTROPHIL RESPONSES - A DIFFERENTIAL EFFECT ON CYTOSOLIC-FREE CA2+

For-Thp-Leu-Ain-OMe and for-Met-Delta(2)Leu-Phe-OMe are two conformati onally restricted fMLP-OMe analogues able to discriminate between diff erent biological responses of human neutrophils. In this paper, we dem onstrate that the former peptide, which evokes only chemotaxis, does n ot alter human neutrophil Ca2+ levels. In contrast, for-Met-Delta(2)Le u-Phe-OMe, which induces superoxide anion release and degranulation bu t not chemotaxis, significantly increases the cation concentration. Th e chelation of Ca2+ in both extracellular and intracellular media abol ishes O-2(-); production triggered by for-Met-Delta(2)Leu-Phe-OMe, whi le the same procedure does not affect neutrophil chemotaxis towards fo r-thp-Leu-Ain-OMe. We therefore suggest that chemotaxis, unlike supero xide anion release, is independent of Ca2+ enhancement in human neutro phils. (C) 1997 Elsevier Science B.V.