Effect of storage on the nitro blue tetrazolium reduction test in dog blood samples

Abstract

IntroductionThe nitro blue tetrazolium (NBT) reduction test (NBTT) has been used for measuring the metabolic activity of phagocytes of mammals. Activated neutrophils transform NBT into formazan in the cytoplasm. The NBTT can detect the activation of neutrophils in peripheral blood and is used to assess neutrophil function in dogs. However, the NBTT is not used frequently in the clinical setting, as samples should be processed after blood collection.ObjectiveThe aim of this study was to evaluate the effect of storage on NBTT in dog blood samples.Materials and MethodsResidual EDTA blood samples from 22 dogs were included of different ages, breeds, and sex. The buffy coat layer was separated from the blood and incubated with 0.1% NBT. The NBTT was performed at 0, 24, 48, and 72 h after the collection of blood. Blood samples were stored at 4°C until the tests were performed. Blood smears were evaluated by light microscopy, and the NBT reduction rate was reported, which represents the percentage of activated neutrophils. The NBT reduction rate was calculated after counting 300 neutrophils in each slide.ResultsThe means of NBTT in dog blood samples at 0, 24, 48, and 72 h were 8.3%, 8.5%, 8.7%, and 7.8%, respectively. No significant differences were observed between time points.ConclusionsThis study showed that the NBTT can be performed up to 72 h after the collection of canine blood if correctly refrigerated at 4°C. This finding supports the performance of the NBTT in the clinical setting.

Exploring the Relationship between Neutrophil Activation and Different States of Canine L. infantum Infection: Nitroblue Tetrazolium Test and IFN-γ

“…Neutrophils that were aggregated or damaged were excluded from the count. The NBT rate was calculated by determining the percentage of activated neutrophils, characterized by the presence of blue-black formazan deposits, among the total counted neutrophils [ 42 ].…”