Determination of rat mast cells by flow-cytometry

Counting of rat mast cells and assessment of degranulation were performed by flow-cytometry using a cytograph. It was shown that the number of mast cells in a total cell population may be obtained rapidly and reproducibly following toluidine blue staining. A dose-response for degranulation by compound 48/80 was performed and it was shown that azure A staining (in 40% sucrose) discriminates degranulated from non-degranulated mast cells, while trypan blue staining discriminates between cytotoxic and non-cytotoxic degranulation. Values obtained by flow-cytometry and microscopic evaluation were in good agreement; assessment by flow-cytometry provides a convenient new approach to counting mast cells and assessing their degree of degranulation.