Some basic conditions for fluorometric measurement of lipase activity of guinea pig peritoneal macrophages were investigated using 4-methylumbelliferyl-oleate as a substrate. The most adequate condition for the assay is as follows:
i ) Enzyme preparation recommended is the supernatant of ultrasonicate after freezing and thawing of guinea pig peritoneal macrophages suspended in distilled water.
ii) Final concentration of buffered substrate should be adjusted at 0.1 mM in acetate buffer, pH 4.5, free from Triton X-100.
iii) Reaction is terminated by addition of 50 mM Tris-HCl buffer, pH 8.6, instead of 50 mM glycine buffer, pH 10.4.