Syncollin secreted by activated human neutrophils targets bacteria

Syncollin is a 16-kDa protein that was originally isolated from the pancreatic zymogen granule. Syncollin is also found in human neutrophils and is secreted from promyelocytic HL-60 cells upon stimulation. Recently, we reported that syncollin is able to bind to bacterial peptidoglycan, to damage the bacterial envelope and to restrict bacterial growth. Here, we show that syncollin is secreted from activated primary human neutrophils, and interacts with extracellular neutrophil traps (NETs) in a similar manner to the well-characterized granular protein myeloperoxidase. In addition, secreted syncollin is able to coat the surface of E. coli in co-cultures of neutrophils and bacteria. On the basis of our findings, we suggest that syncollin plays a role in host defence in the blood. ### Competing Interest Statement The authors have declared no competing interest. * APC : allophycocyanin A.U. : arbitrary units BSA : bovine serum albumin DAPI : 4′,6-diamidino-2-phenylindole FBS : fetal bovine serum FITC : fluorescein isothiocyanate fMLP : N-formylmethionyl-leucyl-phenylalanine MPO : myeloperoxidase NET : neutrophil extracellular trap PBS : phosphate-buffered saline RPMI : Roswell Park Memorial Institute.