Labeling Acidic Compartments of Neutrophils with Cresyl Violet.

We introduce the acidotropic marker cresyl violet to stain acidic granules in live neutrophils. Cresyl violet is less phototoxic, more photostable, and more cost-effective than other commercially available acidotropic markers. Additionally, it does not photoconvert to fluorescent species of a different color, a limitation of other commonly used acidotropic markers. Staining can be readily detected by fluorescence microscopy or by flow cytometry, and can be used as a readout of degranulation in activated neutrophils.