Abstract

Upon activation, neutrophils perform three distinct functions: phagocytosis, degranulation of antimicrobial substances into the extracellular medium, and release of neutrophil extracellular traps. Determination of the nuclear area expansion of neutrophils activated to release neutrophil extracellular traps has become critical in demonstrating early neutrophil activation and has become standard. Here, we demonstrate an automated method for measuring nuclear area expansion in two different mammalian species: canine and bovine. For both species, neutrophils were isolated from peripheral blood and co-incubated with fresh spermatozoa for up to 120 min for canine neutrophil-spermatozoa and recently thawed cryopreserved spermatozoa up to 240 min for bovine neutrophil-spermatozoa. Fluorescence images were acquired using a TissueFAXS microscope and then analyzed using StrataQuest v.7.0 software. The images show the release of neutrophil extracellular traps upon activation with spermatozoa for both species, as evidenced by the co-localization of neutrophil elastase and DNA staining. Neutrophil nuclei were expanded as early as 15 min and were detected at up to 120 min in both species. Analysis by nuclei segmentation showed that the data sets generated for both species were reliable and consistent with previously published methods. The method was developed as an automated alternative for measuring the area expansion of neutrophil nuclei in different species.