Receptor-Mediated Internalization of Fluorescent Chemotactic Peptide by Human Neutrophils

Abstract
Tetramethylrhodamine labeled N -formyl-Nle-Leu-Phe-Nle-Tyr-Lys is a potent chemoattractant for human neutrophils. Binding of this peptide to living neutrophils was observed by means of video intensification microscopy. At 37°C, diffuse membrane fluorescence was seen initially, followed by rapid aggregation and internalization of the fluorescent peptide. These processes are dependent on specific binding to the formyl peptide chemotactic receptor.