I need an easy and straightforward way to measure leukocyte degranulation, mostly neutrophils in vitro. I have considered side scatter and myeloperoxidase substrate reaction, but it didn't work very well.
You can use short 30 minutes stimulation of neutrophils with PMA or fMLP and then in supernate assess elastase activity by spectrofluorimeter or concentration by ELISA.
If you can perform a gelatin zymography, MMP-9 release from tertiary granules of neutrophils is a cheap and easy assay. We have had good results from a short incubation with either TNF or IL-8.