Exocytosis of Neutrophil Formyl peptide receptor-like 1 (fPRL1) results in downregulation of cytoplasmic fPRL1 in patients with purulent dermatitis.

N-Formyl peptide receptor-like 1 (fPRL1) is a member of the chemoattractant subfamily of G protein-coupled receptors and plays a key role in inflammation via chemotaxis and the regulation of mediator release from leukocytes. Activated fPRL1 has recently been shown to induce a complicated pattern of cellular signaling in vitro, but the details of the regulation and alteration of leukocyte cellular fPRL1 during inflammation in vivo remain unclear. To clarify the alteration of neutrophil fPRL1 during inflammation in vivo, the immunohistochemical staining of neutrophil fPRL1 in samples from patients with purulent dermatitis was performed. The in vitro morphological alteration of neutrophil fPRL1 on cellular membranes by stimulation with N-formylmethionyl-leucyl-phenylalanine (fMLP) was also examined. Both the cytoplasm and the cellular membranes of blood neutrophils stained strongly for fPRL1. On the other hand, the cellular membranes of neutrophils in dermatitis tissue stained strongly for fPRL1 but the cytoplasm stained weakly. The enhancement of neutrophil fPRL1 on cellular membranes by stimulation with fMLP indicates the exocytosis of neutrophil fPRL1-containing granules. In conclusion, we for the first time confirmed the alteration of neutrophil fPRL1 in clinical cases of purulent dermatitis. Cytoplasm that was weakly stained and cellular membranes that were well stained for fPRL1 were considered to be distinctive features of activated neutrophils in purulent dermatitis tissue.