New spectrophotometric assays of acid lipase and their use in the diagnosis of Wolman and cholesteryl ester storage diseases.

Trinitrophenylaminolauric acid (TNPAL) was linked to glycerol or cholesterol and the resulting yellow compounds were used as substrates for several lipases and cholesteryl esterase in cells from normal individuals and patients with Wolman's or cholesteryl ester storage diseases. Normal cells (lymphoid cell lines or skin fibroblasts) showed two peaks of lipase or cholesteryl esterase activity at about pH 4.0 and 6.0 each. The activity of the most acidic enzyme, which hydrolyzed natural or synthetic triacylglycerols as well as cholesteryl esters, was considerably reduced in cells derived from patients with Wolman's or cholesteryl ester storage diseases. Simple spectrophotometric procedures were developed for using tri-TNPAL glycerol or TNPAL cholesterol to identify homozygotes of these two respective diseases.